Merge pull request #324 from pf4j/pf4j_3

PF4J 3

.travis.yml

@@ -1,9 +1,5 @@
 language: java
 jdk:
-    - openjdk7
-# JDK7 is not supported anymore; https://github.com/travis-ci/travis-ci/issues/7884#issuecomment-308451879
-#    - oraclejdk7
-    - oraclejdk8
     - openjdk11
 after_success:
   - mvn clean cobertura:cobertura coveralls:report

demo/api/pom.xml

@@ -4,12 +4,12 @@
     <parent>
         <groupId>org.pf4j.demo</groupId>
         <artifactId>pf4j-demo-parent</artifactId>
-        <version>2.7.0-SNAPSHOT</version>
+        <version>3.0.0-SNAPSHOT</version>
     </parent>
 
     <modelVersion>4.0.0</modelVersion>
     <artifactId>pf4j-demo-api</artifactId>
-    <version>2.7.0-SNAPSHOT</version>
+    <version>3.0.0-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>Demo Api</name>
 

demo/app/pom.xml

@@ -4,12 +4,12 @@
     <parent>
         <groupId>org.pf4j.demo</groupId>
         <artifactId>pf4j-demo-parent</artifactId>
-        <version>2.7.0-SNAPSHOT</version>
+        <version>3.0.0-SNAPSHOT</version>
     </parent>
 
     <modelVersion>4.0.0</modelVersion>
     <artifactId>pf4j-demo-app</artifactId>
-    <version>2.7.0-SNAPSHOT</version>
+    <version>3.0.0-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>Demo App</name>
 

demo/app/src/main/java/org/pf4j/demo/Boot.java

@@ -73,8 +73,8 @@ public class Boot {
         }
 
         System.out.println("Extension classes by classpath:");
-        List<Class<Greeting>> greetingsClasses = pluginManager.getExtensionClasses(Greeting.class);
-        for (Class<Greeting> greeting : greetingsClasses) {
+        List<Class<? extends Greeting>> greetingsClasses = pluginManager.getExtensionClasses(Greeting.class);
+        for (Class<? extends Greeting> greeting : greetingsClasses) {
             System.out.println("   Class: " + greeting.getCanonicalName());
         }
 

demo/plugins/plugin1/pom.xml

@@ -4,12 +4,12 @@
     <parent>
         <groupId>org.pf4j.demo</groupId>
         <artifactId>pf4j-demo-plugins</artifactId>
-        <version>2.7.0-SNAPSHOT</version>
+        <version>3.0.0-SNAPSHOT</version>
     </parent>
 
     <modelVersion>4.0.0</modelVersion>
     <artifactId>pf4j-demo-plugin1</artifactId>
-    <version>2.7.0-SNAPSHOT</version>
+    <version>3.0.0-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>Demo Plugin #1</name>
 

demo/plugins/plugin2/pom.xml

@@ -4,12 +4,12 @@
     <parent>
         <groupId>org.pf4j.demo</groupId>
         <artifactId>pf4j-demo-plugins</artifactId>
-        <version>2.7.0-SNAPSHOT</version>
+        <version>3.0.0-SNAPSHOT</version>
     </parent>
 
     <modelVersion>4.0.0</modelVersion>
     <artifactId>pf4j-demo-plugin2</artifactId>
-    <version>2.7.0-SNAPSHOT</version>
+    <version>3.0.0-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>Demo Plugin #2</name>
 

demo/plugins/pom.xml

@@ -4,19 +4,18 @@
     <parent>
         <groupId>org.pf4j.demo</groupId>
         <artifactId>pf4j-demo-parent</artifactId>
-        <version>2.7.0-SNAPSHOT</version>
+        <version>3.0.0-SNAPSHOT</version>
     </parent>
 
     <modelVersion>4.0.0</modelVersion>
     <artifactId>pf4j-demo-plugins</artifactId>
-    <version>2.7.0-SNAPSHOT</version>
+    <version>3.0.0-SNAPSHOT</version>
     <packaging>pom</packaging>
     <name>Demo Plugins Parent</name>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-        <java.version>1.7</java.version>
 
         <!-- Override below properties in each plugin's pom.xml -->
         <plugin.id />
@@ -28,14 +27,6 @@
 
     <build>
         <plugins>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-compiler-plugin</artifactId>
-                <configuration>
-                    <source>${java.version}</source>
-                    <target>${java.version}</target>
-                </configuration>
-            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-assembly-plugin</artifactId>

demo/pom.xml

@@ -4,13 +4,13 @@
     <parent>
         <groupId>org.pf4j</groupId>
         <artifactId>pf4j-parent</artifactId>
-        <version>2.7.0-SNAPSHOT</version>
+        <version>3.0.0-SNAPSHOT</version>
     </parent>
 
     <modelVersion>4.0.0</modelVersion>
     <groupId>org.pf4j.demo</groupId>
     <artifactId>pf4j-demo-parent</artifactId>
-    <version>2.7.0-SNAPSHOT</version>
+    <version>3.0.0-SNAPSHOT</version>
     <packaging>pom</packaging>
     <name>Demo Parent</name>
 

maven-archetypes/quickstart/pom.xml

@@ -0,0 +1,68 @@
+<?xml version="1.0"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <parent>
+        <groupId>org.pf4j</groupId>
+        <artifactId>pf4j-parent</artifactId>
+        <version>3.0.0-SNAPSHOT</version>
+        <relativePath>../../pom.xml</relativePath>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>pf4j-quickstart</artifactId>
+    <packaging>maven-archetype</packaging>
+    <name>Quickstart Archetype</name>
+
+    <build>
+        <!-- http://stackoverflow.com/questions/7223031/how-to-embed-archetype-project-version-in-maven-archetype -->
+        <resources>
+            <resource>
+                <filtering>true</filtering>
+                <directory>src/main/resources</directory>
+                <includes>
+                    <include>archetype-resources/**/pom.xml</include>
+                </includes>
+            </resource>
+
+            <resource>
+                <filtering>false</filtering>
+                <directory>src/main/resources</directory>
+                <excludes>
+                    <exclude>archetype-resources/**/pom.xml</exclude>
+                </excludes>
+            </resource>
+        </resources>
+
+        <extensions>
+            <extension>
+                <groupId>org.apache.maven.archetype</groupId>
+                <artifactId>archetype-packaging</artifactId>
+                <version>2.3</version>
+            </extension>
+        </extensions>
+
+        <pluginManagement>
+            <plugins>
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-archetype-plugin</artifactId>
+                    <version>2.3</version>
+                </plugin>
+
+                <!-- http://stackoverflow.com/questions/7223031/how-to-embed-archetype-project-version-in-maven-archetype -->
+                <plugin>
+                    <groupId>org.apache.maven.plugins</groupId>
+                    <artifactId>maven-resources-plugin</artifactId>
+                    <version>2.5</version>
+                    <configuration>
+                        <delimiters>
+                            <delimiter>{{*}}</delimiter>
+                        </delimiters>
+                        <useDefaultDelimiters>false</useDefaultDelimiters>
+                    </configuration>
+                </plugin>
+            </plugins>
+        </pluginManagement>
+    </build>
+
+</project>

maven-archetypes/quickstart/src/main/resources/META-INF/maven/archetype-metadata.xml

@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<archetype-descriptor name="quickstart">
+
+    <fileSets>
+        <fileSet encoding="UTF-8">
+            <directory></directory>
+            <includes>
+                <include>run.sh</include>
+            </includes>
+        </fileSet>
+    </fileSets>
+
+    <modules>
+        <module id="${rootArtifactId}-app" dir="app" name="${rootArtifactId}-app">
+            <fileSets>
+                <fileSet filtered="true" packaged="true" encoding="UTF-8">
+                    <directory>src/main/java</directory>
+                    <includes>
+                        <include>**/*.java</include>
+                    </includes>
+                </fileSet>
+                <fileSet filtered="true" encoding="UTF-8">
+                    <directory>src/main/resources</directory>
+                    <includes>
+                        <include>**/*.properties</include>
+                    </includes>
+                </fileSet>
+                <fileSet filtered="true" encoding="UTF-8">
+                    <directory>src/main/assembly</directory>
+                    <includes>
+                        <include>**/*.xml</include>
+                    </includes>
+                </fileSet>
+            </fileSets>
+        </module>
+
+        <module id="${rootArtifactId}-plugins" dir="plugins" name="${rootArtifactId}-plugins">
+            <fileSets>
+                <fileSet filtered="true" encoding="UTF-8">
+                    <directory></directory>
+                    <includes>
+                        <include>enabled.txt</include>
+                        <include>disabled.txt</include>
+                    </includes>
+                </fileSet>
+            </fileSets>
+
+            <modules>
+                <module id="hello-plugin" dir="hello" name="hello-plugin">
+                    <fileSets>
+                        <fileSet filtered="true" packaged="true" encoding="UTF-8">
+                            <directory>src/main/java</directory>
+                            <includes>
+                                <include>**/*.java</include>
+                            </includes>
+                        </fileSet>
+                        <fileSet filtered="true" encoding="UTF-8">
+                            <directory></directory>
+                            <includes>
+                                <include>plugin.properties</include>
+                            </includes>
+                        </fileSet>
+                    </fileSets>
+                </module>
+
+                <module id="welcome-plugin" dir="welcome" name="welcome-plugin">
+                    <fileSets>
+                        <fileSet filtered="true" packaged="true" encoding="UTF-8">
+                            <directory>src/main/java</directory>
+                            <includes>
+                                <include>**/*.java</include>
+                            </includes>
+                        </fileSet>
+                        <fileSet filtered="true" encoding="UTF-8">
+                            <directory></directory>
+                            <includes>
+                                <include>plugin.properties</include>
+                            </includes>
+                        </fileSet>
+                    </fileSets>
+                </module>
+            </modules>
+        </module>
+    </modules>
+
+</archetype-descriptor>

maven-archetypes/quickstart/src/main/resources/archetype-resources/app/pom.xml

@@ -0,0 +1,86 @@
+<?xml version="1.0"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <parent>
+        <groupId>${groupId}</groupId>
+        <artifactId>${rootArtifactId}</artifactId>
+        <version>${version}</version>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>${artifactId}</artifactId>
+    <version>${version}</version>
+    <packaging>jar</packaging>
+    <name>App</name>
+
+    <properties>
+        <main.class>${package}.Boot</main.class>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <version>2.3</version>
+                <configuration>
+                    <descriptors>
+                        <descriptor>src/main/assembly/assembly.xml</descriptor>
+                    </descriptors>
+                    <appendAssemblyId>false</appendAssemblyId>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>make-assembly</id>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>attached</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-jar-plugin</artifactId>
+                <version>2.3.1</version>
+                <configuration>
+                    <archive>
+                        <manifest>
+                            <addClasspath>true</addClasspath>
+                            <classpathPrefix>lib/</classpathPrefix>
+                            <mainClass>${main.class}</mainClass>
+                        </manifest>
+                    </archive>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.pf4j</groupId>
+            <artifactId>pf4j</artifactId>
+            <version>${pf4j.version}</version>
+        </dependency>
+
+        <!-- Logs -->
+        <dependency>
+            <groupId>log4j</groupId>
+            <artifactId>log4j</artifactId>
+            <version>1.2.16</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-log4j12</artifactId>
+            <version>${slf4j.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>commons-lang</groupId>
+            <artifactId>commons-lang</artifactId>
+            <version>2.4</version>
+        </dependency>
+    </dependencies>
+
+</project>

maven-archetypes/quickstart/src/main/resources/archetype-resources/app/src/main/assembly/assembly.xml

@@ -0,0 +1,30 @@
+<assembly>
+    <id>app</id>
+    <formats>
+        <format>dir</format>
+        <format>zip</format>
+    </formats>
+    <includeBaseDirectory>false</includeBaseDirectory>
+    <dependencySets>
+        <dependencySet>
+            <useProjectArtifact>false</useProjectArtifact>
+            <outputDirectory>lib</outputDirectory>
+            <includes>
+                <include>*:jar:*</include>
+            </includes>
+        </dependencySet>
+    </dependencySets>
+    <fileSets>
+        <fileSet>
+            <directory>${project.build.directory}</directory>
+            <outputDirectory></outputDirectory>
+            <includes>
+                <include>*.jar</include>
+            </includes>
+            <excludes>
+                <exclude>*-javadoc.jar</exclude>
+                <exclude>*-sources.jar</exclude>
+            </excludes>
+        </fileSet>
+    </fileSets>
+</assembly>

maven-archetypes/quickstart/src/main/resources/archetype-resources/app/src/main/java/Boot.java

@@ -0,0 +1,102 @@
+package ${package};
+
+import org.apache.commons.lang.StringUtils;
+import org.pf4j.DefaultPluginManager;
+import org.pf4j.ExtensionFinder;
+import org.pf4j.PluginManager;
+import org.pf4j.PluginWrapper;
+
+import java.util.List;
+import java.util.Set;
+
+/**
+ * A boot class that start the application.
+ */
+public class Boot {
+
+    public static void main(String[] args) {
+        // create the plugin manager
+        PluginManager pluginManager = new DefaultPluginManager();
+
+        // load the plugins
+        pluginManager.loadPlugins();
+
+        // enable a disabled plugin
+//        pluginManager.enablePlugin("welcome-plugin");
+
+        // start (active/resolved) the plugins
+        pluginManager.startPlugins();
+
+        // retrieves the extensions for Greeting extension point
+        List<Greeting> greetings = pluginManager.getExtensions(Greeting.class);
+        System.out.println(String.format("Found %d extensions for extension point '%s'", greetings.size(), Greeting.class.getName()));
+        for (Greeting greeting : greetings) {
+            System.out.println(">>> " + greeting.getGreeting());
+        }
+
+        // print extensions from classpath (non plugin)
+        System.out.println("Extensions added by classpath:");
+        Set<String> extensionClassNames = pluginManager.getExtensionClassNames(null);
+        for (String extension : extensionClassNames) {
+            System.out.println("   " + extension);
+        }
+
+        System.out.println("Extension classes by classpath:");
+        List<Class<? extends Greeting>> greetingsClasses = pluginManager.getExtensionClasses(Greeting.class);
+        for (Class<? extends Greeting> greeting : greetingsClasses) {
+            System.out.println("   Class: " + greeting.getCanonicalName());
+        }
+
+        // print extensions ids for each started plugin
+        List<PluginWrapper> startedPlugins = pluginManager.getStartedPlugins();
+        for (PluginWrapper plugin : startedPlugins) {
+            String pluginId = plugin.getDescriptor().getPluginId();
+            System.out.println(String.format("Extensions added by plugin '%s':", pluginId));
+            extensionClassNames = pluginManager.getExtensionClassNames(pluginId);
+            for (String extension : extensionClassNames) {
+                System.out.println("   " + extension);
+            }
+        }
+
+        // print extensions instances for Greeting extension point for each started plugin
+        for (PluginWrapper plugin : startedPlugins) {
+            String pluginId = plugin.getDescriptor().getPluginId();
+            System.out.println(String.format("Extensions instances added by plugin '%s' for extension point '%s':", pluginId, Greeting.class.getName()));
+            List<Greeting> extensions = pluginManager.getExtensions(Greeting.class, pluginId);
+            for (Object extension : extensions) {
+                System.out.println("   " + extension);
+            }
+        }
+
+        // print extensions instances from classpath (non plugin)
+        System.out.println("Extensions instances added by classpath:");
+        List extensions = pluginManager.getExtensions((String) null);
+        for (Object extension : extensions) {
+            System.out.println("   " + extension);
+        }
+
+        // print extensions instances for each started plugin
+        for (PluginWrapper plugin : startedPlugins) {
+            String pluginId = plugin.getDescriptor().getPluginId();
+            System.out.println(String.format("Extensions instances added by plugin '%s':", pluginId));
+            extensions = pluginManager.getExtensions(pluginId);
+            for (Object extension : extensions) {
+                System.out.println("   " + extension);
+            }
+        }
+
+        // stop the plugins
+        pluginManager.stopPlugins();
+        /*
+        Runtime.getRuntime().addShutdownHook(new Thread() {
+
+            @Override
+            public void run() {
+                pluginManager.stopPlugins();
+            }
+
+        });
+        */
+    }
+
+}

maven-archetypes/quickstart/src/main/resources/archetype-resources/app/src/main/java/Greeting.java

@@ -0,0 +1,9 @@
+package ${package};
+
+import org.pf4j.ExtensionPoint;
+
+public interface Greeting extends ExtensionPoint {
+
+    String getGreeting();
+
+}

maven-archetypes/quickstart/src/main/resources/archetype-resources/app/src/main/java/WhazzupGreeting.java

@@ -0,0 +1,13 @@
+package ${package};
+
+import org.pf4j.Extension;
+
+@Extension
+public class WhazzupGreeting implements Greeting {
+
+    @Override
+    public String getGreeting() {
+        return "Whazzup";
+    }
+
+}

maven-archetypes/quickstart/src/main/resources/archetype-resources/app/src/main/resources/log4j.properties

@@ -0,0 +1,20 @@
+log4j.rootLogger=DEBUG, Console
+
+#
+# PF4J log
+#
+log4j.logger.org.pf4j=DEBUG, Console
+# !!! Put the bellow classes on level TRACE when you are in trouble
+log4j.logger.org.pf4j.PluginClassLoader=DEBUG, Console
+log4j.logger.org.pf4j.AbstractExtensionFinder=DEBUG, Console
+log4j.additivity.org.pf4j=false
+log4j.additivity.org.pf4j.PluginClassLoader=false
+log4j.additivity.org.pf4j.AbstractExtensionFinder=false
+
+#
+# Appenders
+#
+log4j.appender.Console=org.apache.log4j.ConsoleAppender
+log4j.appender.Console.layout=org.apache.log4j.PatternLayout
+#log4j.appender.Console.layout.conversionPattern=%-5p - %-32.32c{1} - %m\n
+log4j.appender.Console.layout.ConversionPattern=%d %p %c - %m%n

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/disabled.txt

@@ -0,0 +1,6 @@
+########################################
+# - load all plugins except these
+# - add one plugin id on each line
+# - put this file in plugins folder
+########################################
+#welcome-plugin

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/enabled.txt

@@ -0,0 +1,6 @@
+########################################
+# - load only these plugins
+# - add one plugin id on each line
+# - put this file in plugins folder
+########################################
+#welcome-plugin

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/hello/plugin.properties

@@ -0,0 +1,5 @@
+plugin.id=hello-plugin
+plugin.class=${package}.hello.HelloPlugin
+plugin.version=${version}
+plugin.provider=
+plugin.dependencies=

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/hello/pom.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <parent>
+        <groupId>${groupId}</groupId>
+        <artifactId>${rootArtifactId}-plugins</artifactId>
+        <version>${version}</version>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>hello-plugin</artifactId>
+    <version>${version}</version>
+    <packaging>jar</packaging>
+    <name>Hello Plugin</name>
+
+    <properties>
+        <plugin.id>hello-plugin</plugin.id>
+        <plugin.class>${package}.hello.HelloPlugin</plugin.class>
+        <plugin.version>${version}</plugin.version>
+        <plugin.provider/>
+        <plugin.dependencies/>
+    </properties>
+
+</project>

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/hello/src/main/java/hello/HelloPlugin.java

@@ -0,0 +1,37 @@
+package ${package}.hello;
+
+import org.pf4j.Extension;
+import org.pf4j.Plugin;
+import org.pf4j.PluginWrapper;
+import ${package}.Greeting;
+
+/**
+ * A very simple plugin.
+ */
+public class HelloPlugin extends Plugin {
+
+    public HelloPlugin(PluginWrapper wrapper) {
+        super(wrapper);
+    }
+
+    @Override
+    public void start() {
+        System.out.println("HelloPlugin.start()");
+    }
+
+    @Override
+    public void stop() {
+        System.out.println("HelloPlugin.stop()");
+    }
+
+    @Extension(ordinal=1)
+    public static class HelloGreeting implements Greeting {
+
+        @Override
+        public String getGreeting() {
+            return "Hello";
+        }
+
+    }
+
+}

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/pom.xml

@@ -0,0 +1,86 @@
+<?xml version="1.0"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <parent>
+        <groupId>${groupId}</groupId>
+        <artifactId>${rootArtifactId}</artifactId>
+        <version>${version}</version>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>${artifactId}</artifactId>
+    <version>${version}</version>
+    <packaging>pom</packaging>
+    <name>Plugins Parent</name>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+
+        <!-- Override below properties in each plugin's pom.xml -->
+        <plugin.id></plugin.id>
+        <plugin.class></plugin.class>
+        <plugin.version></plugin.version>
+        <plugin.provider></plugin.provider>
+        <plugin.dependencies></plugin.dependencies>
+    </properties>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <version>3.1.0</version>
+                <configuration>
+                    <descriptorRefs>
+                        <descriptorRef>jar-with-dependencies</descriptorRef>
+                    </descriptorRefs>
+                    <finalName>${project.artifactId}-${project.version}-all</finalName>
+                    <appendAssemblyId>false</appendAssemblyId>
+                    <attach>false</attach>
+                    <archive>
+                        <manifest>
+                            <addDefaultImplementationEntries>true</addDefaultImplementationEntries>
+                            <addDefaultSpecificationEntries>true</addDefaultSpecificationEntries>
+                        </manifest>
+                        <manifestEntries>
+                            <Plugin-Id>${plugin.id}</Plugin-Id>
+                            <Plugin-Version>${plugin.version}</Plugin-Version>
+                            <Plugin-Provider>${plugin.provider}</Plugin-Provider>
+                            <Plugin-Class>${plugin.class}</Plugin-Class>
+                            <Plugin-Dependencies>${plugin.dependencies}</Plugin-Dependencies>
+                        </manifestEntries>
+                    </archive>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>make-assembly</id>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>single</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.pf4j</groupId>
+            <artifactId>pf4j</artifactId>
+            <version>${pf4j.version}</version>
+            <!-- !!! VERY IMPORTANT -->
+            <scope>provided</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>${groupId}</groupId>
+            <artifactId>${rootArtifactId}-app</artifactId>
+            <version>${version}</version>
+            <!-- !!! VERY IMPORTANT -->
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+</project>

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/welcome/plugin.properties

@@ -0,0 +1,5 @@
+plugin.id=welcome-plugin
+plugin.class=${package}.welcome.WelcomePlugin
+plugin.version=${version}
+plugin.provider=
+plugin.dependencies=

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/welcome/pom.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <parent>
+        <groupId>${groupId}</groupId>
+        <artifactId>${rootArtifactId}-plugins</artifactId>
+        <version>${version}</version>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>welcome-plugin</artifactId>
+    <version>${version}</version>
+    <packaging>jar</packaging>
+    <name>Welcom Plugin</name>
+
+    <properties>
+        <plugin.id>welcome-plugin</plugin.id>
+        <plugin.class>${package}.welcome.WelcomePlugin</plugin.class>
+        <plugin.version>${version}</plugin.version>
+        <plugin.provider/>
+        <plugin.dependencies/>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>commons-lang</groupId>
+            <artifactId>commons-lang</artifactId>
+            <version>2.6</version>
+        </dependency>
+    </dependencies>
+
+</project>

maven-archetypes/quickstart/src/main/resources/archetype-resources/plugins/welcome/src/main/java/welcome/WelcomePlugin.java

@@ -0,0 +1,41 @@
+package ${package}.welcome;
+
+import org.apache.commons.lang.StringUtils;
+
+import org.pf4j.PluginWrapper;
+import org.pf4j.RuntimeMode;
+import org.pf4j.Extension;
+import org.pf4j.Plugin;
+import ${package}.Greeting;
+
+public class WelcomePlugin extends Plugin {
+
+    public WelcomePlugin(PluginWrapper wrapper) {
+        super(wrapper);
+    }
+
+    @Override
+    public void start() {
+        System.out.println("WelcomePlugin.start()");
+        // for testing the development mode
+        if (RuntimeMode.DEVELOPMENT.equals(wrapper.getRuntimeMode())) {
+            System.out.println(StringUtils.upperCase("WelcomePlugin"));
+        }
+    }
+
+    @Override
+    public void stop() {
+        System.out.println("WelcomePlugin.stop()");
+    }
+
+    @Extension
+    public static class WelcomeGreeting implements Greeting {
+
+        @Override
+        public String getGreeting() {
+            return "Welcome";
+        }
+
+    }
+
+}

maven-archetypes/quickstart/src/main/resources/archetype-resources/pom.xml

@@ -0,0 +1,48 @@
+<?xml version="1.0"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>${groupId}</groupId>
+    <artifactId>${artifactId}</artifactId>
+    <version>${version}</version>
+    <packaging>pom</packaging>
+    <name>PF4J Quickstart</name>
+
+    <repositories>
+        <repository>
+            <id>sonatype-nexus-snapshots</id>
+            <url>https://oss.sonatype.org/content/repositories/snapshots</url>
+            <releases>
+                <enabled>false</enabled>
+            </releases>
+            <snapshots>
+                <enabled>true</enabled>
+            </snapshots>
+        </repository>
+    </repositories>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <maven.compiler.release>8</maven.compiler.release>
+
+        <pf4j.version>{{project.version}}</pf4j.version>
+        <slf4j.version>1.7.7</slf4j.version>
+    </properties>
+
+    <build>
+        <resources>
+            <resource>
+                <filtering>false</filtering>
+                <directory>src/main/java</directory>
+                <excludes>
+                    <exclude>**/*.java</exclude>
+                </excludes>
+            </resource>
+
+            <resource>
+                <directory>src/main/resources</directory>
+            </resource>
+        </resources>
+    </build>
+
+</project>

maven-archetypes/quickstart/src/main/resources/archetype-resources/run.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+# create artifacts using Maven
+mvn clean package -DskipTests
+
+# create "dist" directory
+rm -fr dist
+mkdir -p dist/plugins
+
+# copy plugins to "dist" directory
+cp plugins/*/target/*-all.jar dist/plugins/
+cp plugins/enabled.txt dist/plugins/
+cp plugins/disabled.txt dist/plugins/
+
+cd dist
+
+# unzip app to "dist" directory
+jar xf ../app/target/*.zip
+
+# run app
+java -jar *.jar
+
+cd -

pf4j/pom.xml

@@ -4,12 +4,12 @@
     <parent>
         <groupId>org.pf4j</groupId>
         <artifactId>pf4j-parent</artifactId>
-        <version>2.7.0-SNAPSHOT</version>
+        <version>3.0.0-SNAPSHOT</version>
     </parent>
 
     <modelVersion>4.0.0</modelVersion>
     <artifactId>pf4j</artifactId>
-    <version>2.7.0-SNAPSHOT</version>
+    <version>3.0.0-SNAPSHOT</version>
     <packaging>jar</packaging>
     <name>PF4J</name>
     <description>Plugin Framework for Java</description>
@@ -22,6 +22,35 @@
                 <configuration>
                     <compilerArgument>-proc:none</compilerArgument>
                 </configuration>
+                <executions>
+                    <!-- compile everything for Java 8 except the module-info.java -->
+                    <execution>
+                        <id>default-compile</id>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                        <configuration>
+                            <excludes>
+                                <exclude>module-info.java</exclude>
+                            </excludes>
+                        </configuration>
+                    </execution>
+
+                    <!-- compile module-info.java for Java 9+ -->
+                    <execution>
+                        <id>java9-compile</id>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                        <configuration>
+                            <release>9</release>
+                            <multiReleaseOutput>true</multiReleaseOutput>
+                            <includes>
+                                <include>module-info.java</include>
+                            </includes>
+                        </configuration>
+                    </execution>
+                </executions>
             </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
@@ -29,7 +58,7 @@
                 <configuration>
                     <archive>
                         <manifestEntries>
-                            <Automatic-Module-Name>org.pf4j</Automatic-Module-Name>
+                            <Multi-Release>true</Multi-Release>
                         </manifestEntries>
                     </archive>
                 </configuration>
@@ -69,11 +98,12 @@
         </dependency>
 
         <dependency>
-            <!-- An empty artifact, required while JUnit 4 is on the classpath to override its
-                 dependency on hamcrest.
+            <!-- 
+            An empty artifact, required while JUnit 4 is on the classpath to override its
+            dependency on hamcrest.
 
-                 See http://hamcrest.org/JavaHamcrest/distributables#upgrading-from-hamcrest-1x
-                 -->
+            See http://hamcrest.org/JavaHamcrest/distributables#upgrading-from-hamcrest-1x
+            -->
             <groupId>org.hamcrest</groupId>
             <artifactId>hamcrest-core</artifactId>
             <version>${hamcrest.version}</version>
@@ -81,11 +111,12 @@
         </dependency>
 
         <dependency>
-            <groupId>junit</groupId>
-            <artifactId>junit</artifactId>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
             <version>${junit.version}</version>
             <scope>test</scope>
         </dependency>
+
         <dependency>
             <groupId>org.mockito</groupId>
             <artifactId>mockito-core</artifactId>

pf4j/src/main/java/module-info.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Module descriptor for PF4J.
+ *
+ * @author Decebal Suiu
+ * @author Andreas Rudolph
+ */
+module org.pf4j {
+    requires java.base;
+
+    // provides javax.annotation
+    requires java.compiler;
+
+    // provided by the ASM library
+    requires org.objectweb.asm;
+
+    // The SLF4J library currently does not provide a module.
+    // Version 1.8 provides a module called "org.slf4j". But this version is
+    // currently in beta stage. Therefore I'm not sure, if we already like to
+    // use it.
+    requires slf4j.api;
+
+    // The java-semver library currently does not provide a module.
+    // Maybe we should send them a pull request, that at least they provide an
+    // automatic module name in their MANIFEST file.
+    requires java.semver;
+
+    // Maybe we should reconsider the package hierarchy, that only classes are
+    // exported, which are required by 3rd party developers.
+    exports org.pf4j;
+    exports org.pf4j.processor;
+}

pf4j/src/main/java/org/pf4j/AbstractPluginManager.java

@@ -15,6 +15,10 @@
  */
 package org.pf4j;
 
+import org.pf4j.util.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import java.io.Closeable;
 import java.io.IOException;
 import java.nio.file.Files;
@@ -27,9 +31,6 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import org.pf4j.util.StringUtils;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 
 /**
  * This class implements the boilerplate plugin code that any {@link PluginManager}
@@ -44,6 +45,12 @@ public abstract class AbstractPluginManager implements PluginManager {
 
     private static final Logger log = LoggerFactory.getLogger(AbstractPluginManager.class);
 
+    public static final String PLUGINS_DIR_PROPERTY_NAME = "pf4j.pluginsDir";
+    public static final String MODE_PROPERTY_NAME = "pf4j.mode";
+
+    public static final String DEFAULT_PLUGINS_DIR = "plugins";
+    public static final String DEVELOPMENT_PLUGINS_DIR = "../plugins";
+
     private Path pluginsRoot;
 
     protected ExtensionFinder extensionFinder;
@@ -180,18 +187,12 @@ public abstract class AbstractPluginManager implements PluginManager {
 
         log.debug("Loading plugin from '{}'", pluginPath);
 
-        try {
-            PluginWrapper pluginWrapper = loadPluginFromPath(pluginPath);
+        PluginWrapper pluginWrapper = loadPluginFromPath(pluginPath);
 
-            // try to resolve  the loaded plugin together with other possible plugins that depend on this plugin
-            resolvePlugins();
+        // try to resolve  the loaded plugin together with other possible plugins that depend on this plugin
+        resolvePlugins();
 
-            return pluginWrapper.getDescriptor().getPluginId();
-        } catch (PluginException e) {
-            log.error(e.getMessage(), e);
-        }
-
-        return null;
+        return pluginWrapper.getDescriptor().getPluginId();
     }
 
     /**
@@ -221,7 +222,7 @@ public abstract class AbstractPluginManager implements PluginManager {
         for (Path pluginPath : pluginPaths) {
             try {
                 loadPluginFromPath(pluginPath);
-            } catch (PluginException e) {
+            } catch (PluginRuntimeException e) {
                 log.error(e.getMessage(), e);
             }
         }
@@ -229,7 +230,7 @@ public abstract class AbstractPluginManager implements PluginManager {
         // resolve plugins
         try {
             resolvePlugins();
-        } catch (PluginException e) {
+        } catch (PluginRuntimeException e) {
             log.error(e.getMessage(), e);
         }
     }
@@ -275,7 +276,7 @@ public abstract class AbstractPluginManager implements PluginManager {
                     try {
                         ((Closeable) classLoader).close();
                     } catch (IOException e) {
-                        log.error("Cannot close classloader", e);
+                        throw new PluginRuntimeException(e, "Cannot close classloader");
                     }
                 }
             }
@@ -293,23 +294,24 @@ public abstract class AbstractPluginManager implements PluginManager {
         checkPluginId(pluginId);
 
         PluginWrapper pluginWrapper = getPlugin(pluginId);
+        // stop the plugin if it's started
         PluginState pluginState = stopPlugin(pluginId);
         if (PluginState.STARTED == pluginState) {
             log.error("Failed to stop plugin '{}' on delete", pluginId);
             return false;
         }
 
+        // get an instance of plugin before the plugin is unloaded
+        // for reason see https://github.com/pf4j/pf4j/issues/309
+        Plugin plugin = pluginWrapper.getPlugin();
+
         if (!unloadPlugin(pluginId)) {
             log.error("Failed to unload plugin '{}' on delete", pluginId);
             return false;
         }
 
-        try {
-            pluginWrapper.getPlugin().delete();
-        } catch (PluginException e) {
-            log.error(e.getMessage(), e);
-            return false;
-        }
+        // notify the plugin as it's deleted
+        plugin.delete();
 
         Path pluginPath = pluginWrapper.getPluginPath();
 
@@ -369,16 +371,12 @@ public abstract class AbstractPluginManager implements PluginManager {
             startPlugin(dependency.getPluginId());
         }
 
-        try {
-            log.info("Start plugin '{}'", getPluginLabel(pluginDescriptor));
-            pluginWrapper.getPlugin().start();
-            pluginWrapper.setPluginState(PluginState.STARTED);
-            startedPlugins.add(pluginWrapper);
+        log.info("Start plugin '{}'", getPluginLabel(pluginDescriptor));
+        pluginWrapper.getPlugin().start();
+        pluginWrapper.setPluginState(PluginState.STARTED);
+        startedPlugins.add(pluginWrapper);
 
-            firePluginStateEvent(new PluginStateEvent(this, pluginWrapper, pluginState));
-        } catch (PluginException e) {
-            log.error(e.getMessage(), e);
-        }
+        firePluginStateEvent(new PluginStateEvent(this, pluginWrapper, pluginState));
 
         return pluginWrapper.getPluginState();
     }
@@ -402,7 +400,7 @@ public abstract class AbstractPluginManager implements PluginManager {
                     itr.remove();
 
                     firePluginStateEvent(new PluginStateEvent(this, pluginWrapper, pluginState));
-                } catch (PluginException e) {
+                } catch (PluginRuntimeException e) {
                     log.error(e.getMessage(), e);
                 }
             }
@@ -443,16 +441,12 @@ public abstract class AbstractPluginManager implements PluginManager {
             }
         }
 
-        try {
-            log.info("Stop plugin '{}'", getPluginLabel(pluginDescriptor));
-            pluginWrapper.getPlugin().stop();
-            pluginWrapper.setPluginState(PluginState.STOPPED);
-            startedPlugins.remove(pluginWrapper);
+        log.info("Stop plugin '{}'", getPluginLabel(pluginDescriptor));
+        pluginWrapper.getPlugin().stop();
+        pluginWrapper.setPluginState(PluginState.STOPPED);
+        startedPlugins.remove(pluginWrapper);
 
-            firePluginStateEvent(new PluginStateEvent(this, pluginWrapper, pluginState));
-        } catch (PluginException e) {
-            log.error(e.getMessage(), e);
-        }
+        firePluginStateEvent(new PluginStateEvent(this, pluginWrapper, pluginState));
 
         return pluginWrapper.getPluginState();
     }
@@ -480,10 +474,7 @@ public abstract class AbstractPluginManager implements PluginManager {
 
             firePluginStateEvent(new PluginStateEvent(this, pluginWrapper, PluginState.STOPPED));
 
-            if (!pluginStatusProvider.disablePlugin(pluginId)) {
-                return false;
-            }
-
+            pluginStatusProvider.disablePlugin(pluginId);
             log.info("Disabled plugin '{}'", getPluginLabel(pluginDescriptor));
 
             return true;
@@ -509,9 +500,7 @@ public abstract class AbstractPluginManager implements PluginManager {
             return true;
         }
 
-        if (!pluginStatusProvider.enablePlugin(pluginId)) {
-            return false;
-        }
+        pluginStatusProvider.enablePlugin(pluginId);
 
         pluginWrapper.setPluginState(PluginState.CREATED);
 
@@ -539,55 +528,28 @@ public abstract class AbstractPluginManager implements PluginManager {
             Class<?> c = extensionWrapper.getDescriptor().extensionClass;
             extensionClasses.add(c);
         }
+
         return extensionClasses;
     }
 
-    @SuppressWarnings("unchecked")
     @Override
-    public <T> List<Class<T>> getExtensionClasses(Class<T> type) {
-        List<ExtensionWrapper<T>> extensionsWrapper = extensionFinder.find(type);
-        List<Class<T>> extensionClasses = new ArrayList<>(extensionsWrapper.size());
-        for (ExtensionWrapper<T> extensionWrapper : extensionsWrapper) {
-            Class<T> c = (Class<T>) extensionWrapper.getDescriptor().extensionClass;
-            extensionClasses.add(c);
-        }
-
-        return extensionClasses;
+    public <T> List<Class<? extends T>> getExtensionClasses(Class<T> type) {
+        return getExtensionClasses(extensionFinder.find(type));
     }
 
-    @SuppressWarnings("unchecked")
     @Override
-    public <T> List<Class<T>> getExtensionClasses(Class<T> type, String pluginId) {
-        List<ExtensionWrapper<T>> extensionsWrapper = extensionFinder.find(type, pluginId);
-        List<Class<T>> extensionClasses = new ArrayList<>(extensionsWrapper.size());
-        for (ExtensionWrapper<T> extensionWrapper : extensionsWrapper) {
-            Class<T> c = (Class<T>) extensionWrapper.getDescriptor().extensionClass;
-            extensionClasses.add(c);
-        }
-
-        return extensionClasses;
+    public <T> List<Class<? extends T>> getExtensionClasses(Class<T> type, String pluginId) {
+        return getExtensionClasses(extensionFinder.find(type, pluginId));
     }
 
     @Override
     public <T> List<T> getExtensions(Class<T> type) {
-        List<ExtensionWrapper<T>> extensionsWrapper = extensionFinder.find(type);
-        List<T> extensions = new ArrayList<>(extensionsWrapper.size());
-        for (ExtensionWrapper<T> extensionWrapper : extensionsWrapper) {
-            extensions.add(extensionWrapper.getExtension());
-        }
-
-        return extensions;
+        return getExtensions(extensionFinder.find(type));
     }
 
     @Override
     public <T> List<T> getExtensions(Class<T> type, String pluginId) {
-        List<ExtensionWrapper<T>> extensionsWrapper = extensionFinder.find(type, pluginId);
-        List<T> extensions = new ArrayList<>(extensionsWrapper.size());
-        for (ExtensionWrapper<T> extensionWrapper : extensionsWrapper) {
-            extensions.add(extensionWrapper.getExtension());
-        }
-
-        return extensions;
+        return getExtensions(extensionFinder.find(type, pluginId));
     }
 
     @Override
@@ -596,7 +558,11 @@ public abstract class AbstractPluginManager implements PluginManager {
         List<ExtensionWrapper> extensionsWrapper = extensionFinder.find(pluginId);
         List extensions = new ArrayList<>(extensionsWrapper.size());
         for (ExtensionWrapper extensionWrapper : extensionsWrapper) {
-            extensions.add(extensionWrapper.getExtension());
+            try {
+                extensions.add(extensionWrapper.getExtension());
+            } catch (PluginRuntimeException e) {
+                log.error("Cannot retrieve extension", e);
+            }
         }
 
         return extensions;
@@ -612,7 +578,6 @@ public abstract class AbstractPluginManager implements PluginManager {
         return extensionFactory;
     }
 
-    // TODO remove
     public PluginLoader getPluginLoader() {
         return pluginLoader;
     }
@@ -625,7 +590,7 @@ public abstract class AbstractPluginManager implements PluginManager {
     public RuntimeMode getRuntimeMode() {
         if (runtimeMode == null) {
             // retrieves the runtime mode from system
-            String modeAsString = System.getProperty("pf4j.mode", RuntimeMode.DEPLOYMENT.toString());
+            String modeAsString = System.getProperty(MODE_PROPERTY_NAME, RuntimeMode.DEPLOYMENT.toString());
             runtimeMode = RuntimeMode.byName(modeAsString);
         }
 
@@ -723,20 +688,16 @@ public abstract class AbstractPluginManager implements PluginManager {
 
     /**
      * Add the possibility to override the plugins root.
-     * If a {@code pf4j.pluginsDir} system property is defined than this method returns that root.
-     * If {@link #getRuntimeMode()} returns {@link RuntimeMode#DEVELOPMENT} than {@code ../plugins}
-     * is returned else this method returns {@code plugins}.
+     * If a {@link #PLUGINS_DIR_PROPERTY_NAME} system property is defined than this method returns that root.
+     * If {@link #getRuntimeMode()} returns {@link RuntimeMode#DEVELOPMENT} than {@link #DEVELOPMENT_PLUGINS_DIR}
+     * is returned else this method returns {@link #DEFAULT_PLUGINS_DIR}.
      *
      * @return the plugins root
      */
     protected Path createPluginsRoot() {
-        String pluginsDir = System.getProperty("pf4j.pluginsDir");
+        String pluginsDir = System.getProperty(PLUGINS_DIR_PROPERTY_NAME);
         if (pluginsDir == null) {
-            if (isDevelopment()) {
-                pluginsDir = "../plugins";
-            } else {
-                pluginsDir = "plugins";
-            }
+            pluginsDir = isDevelopment() ? DEVELOPMENT_PLUGINS_DIR : DEFAULT_PLUGINS_DIR;
         }
 
         return Paths.get(pluginsDir);
@@ -771,7 +732,7 @@ public abstract class AbstractPluginManager implements PluginManager {
         return pluginStatusProvider.isPluginDisabled(pluginId);
     }
 
-    protected void resolvePlugins() throws PluginException {
+    protected void resolvePlugins() {
         // retrieves the plugins descriptors
         List<PluginDescriptor> descriptors = new ArrayList<>();
         for (PluginWrapper plugin : plugins.values()) {
@@ -820,7 +781,7 @@ public abstract class AbstractPluginManager implements PluginManager {
         }
     }
 
-    protected PluginWrapper loadPluginFromPath(Path pluginPath) throws PluginException {
+    protected PluginWrapper loadPluginFromPath(Path pluginPath) {
         // Test for plugin path duplication
         String pluginId = idForPath(pluginPath);
         if (pluginId != null) {
@@ -838,7 +799,7 @@ public abstract class AbstractPluginManager implements PluginManager {
         pluginId = pluginDescriptor.getPluginId();
         if (plugins.containsKey(pluginId)) {
             PluginWrapper loadedPlugin = getPlugin(pluginId);
-            throw new PluginException("There is an already loaded plugin ({}) "
+            throw new PluginRuntimeException("There is an already loaded plugin ({}) "
                     + "with the same id ({}) as the plugin at path '{}'. Simultaneous loading "
                     + "of plugins with the same PluginId is not currently supported.\n"
                     + "As a workaround you may include PluginVersion and PluginProvider "
@@ -859,7 +820,6 @@ public abstract class AbstractPluginManager implements PluginManager {
         log.debug("Creating wrapper for plugin '{}'", pluginPath);
         PluginWrapper pluginWrapper = new PluginWrapper(this, pluginDescriptor, pluginPath, pluginClassLoader);
         pluginWrapper.setPluginFactory(getPluginFactory());
-        pluginWrapper.setRuntimeMode(getRuntimeMode());
 
         // test for disabled plugin
         if (isPluginDisabled(pluginDescriptor.getPluginId())) {
@@ -907,23 +867,18 @@ public abstract class AbstractPluginManager implements PluginManager {
      * Override this to change the validation criteria.
      *
      * @param descriptor the plugin descriptor to validate
-     * @throws PluginException if validation fails
+     * @throws PluginRuntimeException if validation fails
      */
-    protected void validatePluginDescriptor(PluginDescriptor descriptor) throws PluginException {
+    protected void validatePluginDescriptor(PluginDescriptor descriptor) {
         if (StringUtils.isNullOrEmpty(descriptor.getPluginId())) {
-            throw new PluginException("Field 'id' cannot be empty");
+            throw new PluginRuntimeException("Field 'id' cannot be empty");
         }
 
         if (descriptor.getVersion() == null) {
-            throw new PluginException("Field 'version' cannot be empty");
+            throw new PluginRuntimeException("Field 'version' cannot be empty");
         }
     }
 
-    // TODO add this method in PluginManager as default method for Java 8.
-    protected boolean isDevelopment() {
-        return RuntimeMode.DEVELOPMENT.equals(getRuntimeMode());
-    }
-
     /**
      * @return true if exact versions in requires is allowed
      */
@@ -954,4 +909,28 @@ public abstract class AbstractPluginManager implements PluginManager {
         return pluginDescriptor.getPluginId() + "@" + pluginDescriptor.getVersion();
     }
 
+    @SuppressWarnings("unchecked")
+    private <T> List<Class<? extends T>> getExtensionClasses(List<ExtensionWrapper<T>> extensionsWrapper) {
+        List<Class<? extends T>> extensionClasses = new ArrayList<>(extensionsWrapper.size());
+        for (ExtensionWrapper<T> extensionWrapper : extensionsWrapper) {
+            Class<T> c = (Class<T>) extensionWrapper.getDescriptor().extensionClass;
+            extensionClasses.add(c);
+        }
+
+        return extensionClasses;
+    }
+
+    private <T> List<T> getExtensions(List<ExtensionWrapper<T>> extensionsWrapper) {
+        List<T> extensions = new ArrayList<>(extensionsWrapper.size());
+        for (ExtensionWrapper<T> extensionWrapper : extensionsWrapper) {
+            try {
+                extensions.add(extensionWrapper.getExtension());
+            } catch (PluginRuntimeException e) {
+                log.error("Cannot retrieve extension", e);
+            }
+        }
+
+        return extensions;
+    }
+
 }

pf4j/src/main/java/org/pf4j/BasePluginLoader.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+import org.pf4j.util.FileUtils;
+
+import java.io.File;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+
+/**
+ * Load all information needed by a plugin.
+ * This means add to the plugin's {@link ClassLoader} all the jar files and
+ * all the class files specified in the {@link PluginClasspath}.
+ *
+ * @author Decebal Suiu
+ */
+public class BasePluginLoader implements PluginLoader {
+
+    protected PluginManager pluginManager;
+    protected PluginClasspath pluginClasspath;
+
+    public BasePluginLoader(PluginManager pluginManager, PluginClasspath pluginClasspath) {
+        this.pluginManager = pluginManager;
+        this.pluginClasspath = pluginClasspath;
+    }
+
+    @Override
+    public boolean isApplicable(Path pluginPath) {
+        return Files.exists(pluginPath);
+    }
+
+    @Override
+    public ClassLoader loadPlugin(Path pluginPath, PluginDescriptor pluginDescriptor) {
+        PluginClassLoader pluginClassLoader = createPluginClassLoader(pluginPath, pluginDescriptor);
+
+        loadClasses(pluginPath, pluginClassLoader);
+        loadJars(pluginPath, pluginClassLoader);
+
+        return pluginClassLoader;
+    }
+
+    protected PluginClassLoader createPluginClassLoader(Path pluginPath, PluginDescriptor pluginDescriptor) {
+        return new PluginClassLoader(pluginManager, pluginDescriptor, getClass().getClassLoader());
+    }
+
+    /**
+     * Add all {@code *.class} files from {@link PluginClasspath#getClassesDirectories()}
+     * to the plugin's {@link ClassLoader}.
+     */
+    protected void loadClasses(Path pluginPath, PluginClassLoader pluginClassLoader) {
+        for (String directory : pluginClasspath.getClassesDirectories()) {
+            File file = pluginPath.resolve(directory).toFile();
+            if (file.exists() && file.isDirectory()) {
+                pluginClassLoader.addFile(file);
+            }
+        }
+    }
+
+    /**
+     * Add all {@code *.jar} files from {@link PluginClasspath#getJarsDirectories()}
+     * to the plugin's {@link ClassLoader}.
+     */
+    protected void loadJars(Path pluginPath, PluginClassLoader pluginClassLoader) {
+        for (String jarsDirectory : pluginClasspath.getJarsDirectories()) {
+            Path file = pluginPath.resolve(jarsDirectory);
+            List<File> jars = FileUtils.getJars(file);
+            for (File jar : jars) {
+                pluginClassLoader.addFile(jar);
+            }
+        }
+    }
+
+}

pf4j/src/main/java/org/pf4j/BasePluginRepository.java

@@ -48,14 +48,7 @@ public class BasePluginRepository implements PluginRepository {
         this.filter = filter;
 
         // last modified file is first
-        this.comparator = new Comparator<File>() {
-
-            @Override
-            public int compare(File o1, File o2) {
-                return (int) (o2.lastModified() - o1.lastModified());
-            }
-
-        };
+        this.comparator = (o1, o2) -> (int) (o2.lastModified() - o1.lastModified());
     }
 
     public void setFilter(FileFilter filter) {
@@ -94,13 +87,17 @@ public class BasePluginRepository implements PluginRepository {
 
     @Override
     public boolean deletePluginPath(Path pluginPath) {
+        if (!filter.accept(pluginPath.toFile())) {
+            return false;
+        }
+
         try {
             FileUtils.delete(pluginPath);
             return true;
-        } catch (NoSuchFileException nsf) {
-            return false; // Return false on not found to be compatible with previous API
+        } catch (NoSuchFileException e) {
+            return false; // Return false on not found to be compatible with previous API (#135)
         } catch (IOException e) {
-            throw new RuntimeException(e);
+            throw new PluginRuntimeException(e);
         }
     }
 

pf4j/src/main/java/org/pf4j/CompoundPluginDescriptorFinder.java

@@ -57,7 +57,7 @@ public class CompoundPluginDescriptorFinder implements PluginDescriptorFinder {
     }
 
     @Override
-    public PluginDescriptor find(Path pluginPath) throws PluginException {
+    public PluginDescriptor find(Path pluginPath) {
         for (PluginDescriptorFinder finder : finders) {
             if (finder.isApplicable(pluginPath)) {
                 log.debug("'{}' is applicable for plugin '{}'", finder, pluginPath);
@@ -81,7 +81,7 @@ public class CompoundPluginDescriptorFinder implements PluginDescriptorFinder {
             }
         }
 
-        throw new PluginException("No PluginDescriptorFinder for plugin '{}'", pluginPath);
+        throw new PluginRuntimeException("No PluginDescriptorFinder for plugin '{}'", pluginPath);
     }
 
 }

pf4j/src/main/java/org/pf4j/CompoundPluginLoader.java

@@ -21,6 +21,7 @@ import org.slf4j.LoggerFactory;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.function.BooleanSupplier;
 
 /**
  * @author Decebal Suiu
@@ -41,6 +42,21 @@ public class CompoundPluginLoader implements PluginLoader {
         return this;
     }
 
+    /**
+     * Add a {@link PluginLoader} only if the {@code condition} is satisfied.
+     *
+     * @param loader
+     * @param condition
+     * @return
+     */
+    public CompoundPluginLoader add(PluginLoader loader, BooleanSupplier condition) {
+        if (condition.getAsBoolean()) {
+            return add(loader);
+        }
+
+        return this;
+    }
+
     public int size() {
         return loaders.size();
     }

pf4j/src/main/java/org/pf4j/CompoundPluginRepository.java

@@ -17,7 +17,10 @@ package org.pf4j;
 
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
+import java.util.function.BooleanSupplier;
 
 /**
  * @author Decebal Suiu
@@ -37,14 +40,29 @@ public class CompoundPluginRepository implements PluginRepository {
         return this;
     }
 
+    /**
+     * Add a {@link PluginRepository} only if the {@code condition} is satisfied.
+     *
+     * @param repository
+     * @param condition
+     * @return
+     */
+    public CompoundPluginRepository add(PluginRepository repository, BooleanSupplier condition) {
+        if (condition.getAsBoolean()) {
+            return add(repository);
+        }
+
+        return this;
+    }
+
     @Override
     public List<Path> getPluginPaths() {
-        List<Path> paths = new ArrayList<>();
+        Set<Path> paths = new LinkedHashSet<>();
         for (PluginRepository repository : repositories) {
             paths.addAll(repository.getPluginPaths());
         }
 
-        return paths;
+        return new ArrayList<>(paths);
     }
 
     @Override

pf4j/src/main/java/org/pf4j/DefaultExtensionFactory.java

@@ -29,20 +29,16 @@ public class DefaultExtensionFactory implements ExtensionFactory {
     private static final Logger log = LoggerFactory.getLogger(DefaultExtensionFactory.class);
 
     /**
-     * Creates an extension instance. If an error occurs than that error is logged and the method returns {@code null}.
-     * @param extensionClass
-     * @return
+     * Creates an extension instance.
      */
     @Override
-    public Object create(Class<?> extensionClass) {
+    public <T> T create(Class<T> extensionClass) {
         log.debug("Create instance for extension '{}'", extensionClass.getName());
         try {
             return extensionClass.newInstance();
         } catch (Exception e) {
-            log.error(e.getMessage(), e);
+            throw new PluginRuntimeException(e);
         }
-
-        return null;
     }
 
 }

pf4j/src/main/java/org/pf4j/DefaultPluginClasspath.java

@@ -16,17 +16,20 @@
 package org.pf4j;
 
 /**
- * The default values are {@code classes} and {@code lib}.
+ * The default values are {@link #CLASSES_DIR} and {@code #LIB_DIR}.
  *
  * @author Decebal Suiu
  */
 public class DefaultPluginClasspath extends PluginClasspath {
 
+    public static final String CLASSES_DIR = "classes";
+    public static final String LIB_DIR = "lib";
+
     public DefaultPluginClasspath() {
         super();
 
-        addClassesDirectories("classes");
-        addLibDirectories("lib");
+        addClassesDirectories(CLASSES_DIR);
+        addJarsDirectories(LIB_DIR);
     }
 
 }

pf4j/src/main/java/org/pf4j/DefaultPluginLoader.java

@@ -15,72 +15,23 @@
  */
 package org.pf4j;
 
-import org.pf4j.util.FileUtils;
-
-import java.io.File;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.List;
 
 /**
- * Load all information needed by a plugin.
- * This means add to classpath all jar files from {@code lib} directory
- * and all class files from {@code classes}.
+ * Load all information needed by a plugin from {@link DefaultPluginClasspath}.
  *
  * @author Decebal Suiu
  */
-public class DefaultPluginLoader implements PluginLoader {
-
-    protected PluginManager pluginManager;
-    protected PluginClasspath pluginClasspath;
+public class DefaultPluginLoader extends BasePluginLoader {
 
-    public DefaultPluginLoader(PluginManager pluginManager, PluginClasspath pluginClasspath) {
-        this.pluginManager = pluginManager;
-        this.pluginClasspath = pluginClasspath;
+    public DefaultPluginLoader(PluginManager pluginManager) {
+        super(pluginManager, new DefaultPluginClasspath());
     }
 
     @Override
     public boolean isApplicable(Path pluginPath) {
-        return Files.exists(pluginPath) && Files.isDirectory(pluginPath);
-    }
-
-    @Override
-    public ClassLoader loadPlugin(Path pluginPath, PluginDescriptor pluginDescriptor) {
-        PluginClassLoader pluginClassLoader = createPluginClassLoader(pluginPath, pluginDescriptor);
-
-        loadClasses(pluginPath, pluginClassLoader);
-        loadJars(pluginPath, pluginClassLoader);
-
-        return pluginClassLoader;
-    }
-
-    protected PluginClassLoader createPluginClassLoader(Path pluginPath, PluginDescriptor pluginDescriptor) {
-        return new PluginClassLoader(pluginManager, pluginDescriptor, getClass().getClassLoader());
-    }
-
-    /**
-     * Add all {@code *.class} files from {@code classes} directories to plugin class loader.
-     */
-    protected void loadClasses(Path pluginPath, PluginClassLoader pluginClassLoader) {
-        for (String directory : pluginClasspath.getClassesDirectories()) {
-            File file = pluginPath.resolve(directory).toFile();
-            if (file.exists() && file.isDirectory()) {
-                pluginClassLoader.addFile(file);
-            }
-        }
-    }
-
-    /**
-     * Add all {@code *.jar} files from {@code lib} directories to plugin class loader.
-     */
-    protected void loadJars(Path pluginPath, PluginClassLoader pluginClassLoader) {
-        for (String libDirectory : pluginClasspath.getLibDirectories()) {
-            Path file = pluginPath.resolve(libDirectory);
-            List<File> jars = FileUtils.getJars(file);
-            for (File jar : jars) {
-                pluginClassLoader.addFile(jar);
-            }
-        }
+        return super.isApplicable(pluginPath) && Files.isDirectory(pluginPath);
     }
 
 }

pf4j/src/main/java/org/pf4j/DefaultPluginManager.java

@@ -19,12 +19,13 @@ import org.pf4j.util.FileUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import java.io.File;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 
 /**
  * Default implementation of the {@link PluginManager} interface.
+ * In essence it is a {@link ZipPluginManager} plus a {@link JarPluginManager}.
+ * So, it can load plugins from jar and zip, simultaneous.
  *
  * <p>This class is not thread-safe.
  *
@@ -34,22 +35,12 @@ public class DefaultPluginManager extends AbstractPluginManager {
 
     private static final Logger log = LoggerFactory.getLogger(DefaultPluginManager.class);
 
-    protected PluginClasspath pluginClasspath;
+    public static final String PLUGINS_DIR_CONFIG_PROPERTY_NAME = "pf4j.pluginsConfigDir";
 
     public DefaultPluginManager() {
         super();
     }
 
-    /**
-     * Use {@link DefaultPluginManager#DefaultPluginManager(Path)}.
-     *
-     * @param pluginsDir
-     */
-    @Deprecated
-    public DefaultPluginManager(File pluginsDir) {
-        this(pluginsDir.toPath());
-    }
-
     public DefaultPluginManager(Path pluginsRoot) {
         super(pluginsRoot);
     }
@@ -81,23 +72,26 @@ public class DefaultPluginManager extends AbstractPluginManager {
 
     @Override
     protected PluginStatusProvider createPluginStatusProvider() {
-        String configDir = System.getProperty("pf4j.pluginsConfigDir");
+        String configDir = System.getProperty(PLUGINS_DIR_CONFIG_PROPERTY_NAME);
         Path configPath = configDir != null ? Paths.get(configDir) : getPluginsRoot();
+
         return new DefaultPluginStatusProvider(configPath);
     }
 
     @Override
     protected PluginRepository createPluginRepository() {
         return new CompoundPluginRepository()
-            .add(new DefaultPluginRepository(getPluginsRoot(), isDevelopment()))
-            .add(new JarPluginRepository(getPluginsRoot()));
+            .add(new DevelopmentPluginRepository(getPluginsRoot()), this::isDevelopment)
+            .add(new JarPluginRepository(getPluginsRoot()), this::isNotDevelopment)
+            .add(new DefaultPluginRepository(getPluginsRoot()), this::isNotDevelopment);
     }
 
     @Override
     protected PluginLoader createPluginLoader() {
         return new CompoundPluginLoader()
-            .add(new DefaultPluginLoader(this, pluginClasspath))
-            .add(new JarPluginLoader(this));
+            .add(new DevelopmentPluginLoader(this), this::isDevelopment)
+            .add(new JarPluginLoader(this), this::isNotDevelopment)
+            .add(new DefaultPluginLoader(this), this::isNotDevelopment);
     }
 
     @Override
@@ -105,19 +99,8 @@ public class DefaultPluginManager extends AbstractPluginManager {
         return new DefaultVersionManager();
     }
 
-    /**
-     * By default if {@link DefaultPluginManager#isDevelopment()} returns true
-     * than a {@link DevelopmentPluginClasspath} is returned
-     * else this method returns {@link DefaultPluginClasspath}.
-     */
-    protected PluginClasspath createPluginClasspath() {
-        return isDevelopment() ? new DevelopmentPluginClasspath() : new DefaultPluginClasspath();
-    }
-
     @Override
     protected void initialize() {
-        pluginClasspath = createPluginClasspath();
-
         super.initialize();
 
         if (isDevelopment()) {
@@ -128,13 +111,14 @@ public class DefaultPluginManager extends AbstractPluginManager {
     }
 
     /**
-     * Load a plugin from disk. If the path is a zip file, first unpack
+     * Load a plugin from disk. If the path is a zip file, first unpack.
+     *
      * @param pluginPath plugin location on disk
      * @return PluginWrapper for the loaded plugin or null if not loaded
-     * @throws PluginException if problems during load
+     * @throws PluginRuntimeException if problems during load
      */
     @Override
-    protected PluginWrapper loadPluginFromPath(Path pluginPath) throws PluginException {
+    protected PluginWrapper loadPluginFromPath(Path pluginPath) {
         // First unzip any ZIP files
         try {
             pluginPath = FileUtils.expandIfZip(pluginPath);

pf4j/src/main/java/org/pf4j/DefaultPluginRepository.java

@@ -24,7 +24,6 @@ import org.pf4j.util.OrFileFilter;
 import org.pf4j.util.ZipFileFilter;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import org.pf4j.util.NameFileFilter;
 
 import java.io.File;
 import java.io.FileFilter;
@@ -39,29 +38,17 @@ public class DefaultPluginRepository extends BasePluginRepository {
 
     private static final Logger log = LoggerFactory.getLogger(DefaultPluginRepository.class);
 
-    public DefaultPluginRepository(Path pluginsRoot, boolean development) {
+    public DefaultPluginRepository(Path pluginsRoot) {
         super(pluginsRoot);
 
         AndFileFilter pluginsFilter = new AndFileFilter(new DirectoryFileFilter());
-        pluginsFilter.addFileFilter(new NotFileFilter(createHiddenPluginFilter(development)));
+        pluginsFilter.addFileFilter(new NotFileFilter(createHiddenPluginFilter()));
         setFilter(pluginsFilter);
     }
 
     @Override
     public List<Path> getPluginPaths() {
-        // expand plugins zip files
-        File[] pluginZips = pluginsRoot.toFile().listFiles(new ZipFileFilter());
-        if ((pluginZips != null) && pluginZips.length > 0) {
-            for (File pluginZip : pluginZips) {
-                try {
-                    FileUtils.expandIfZip(pluginZip.toPath());
-                } catch (IOException e) {
-                    log.error("Cannot expand plugin zip '{}'", pluginZip);
-                    log.error(e.getMessage(), e);
-                }
-            }
-        }
-
+        extractZipFiles();
         return super.getPluginPaths();
     }
 
@@ -71,16 +58,23 @@ public class DefaultPluginRepository extends BasePluginRepository {
         return super.deletePluginPath(pluginPath);
     }
 
-    protected FileFilter createHiddenPluginFilter(boolean development) {
-        OrFileFilter hiddenPluginFilter = new OrFileFilter(new HiddenFilter());
+    protected FileFilter createHiddenPluginFilter() {
+        return new OrFileFilter(new HiddenFilter());
+    }
 
-        if (development) {
-            // skip default build output folders since these will cause errors in the logs
-            hiddenPluginFilter
-                .addFileFilter(new NameFileFilter("target")) // MAVEN
-                .addFileFilter(new NameFileFilter("build")); // GRADLE
+    private void extractZipFiles() {
+        // expand plugins zip files
+        File[] zipFiles = pluginsRoot.toFile().listFiles(new ZipFileFilter());
+        if ((zipFiles != null) && zipFiles.length > 0) {
+            for (File pluginZip : zipFiles) {
+                try {
+                    FileUtils.expandIfZip(pluginZip.toPath());
+                } catch (IOException e) {
+                    log.error("Cannot expand plugin zip '{}'", pluginZip);
+                    log.error(e.getMessage(), e);
+                }
+            }
         }
-
-        return hiddenPluginFilter;
     }
+
 }

pf4j/src/main/java/org/pf4j/DefaultPluginStatusProvider.java

@@ -66,31 +66,23 @@ public class DefaultPluginStatusProvider implements PluginStatusProvider {
     }
 
     @Override
-    public boolean disablePlugin(String pluginId) {
-        if (disabledPlugins.add(pluginId)) {
-            try {
-                FileUtils.writeLines(disabledPlugins, pluginsRoot.resolve("disabled.txt").toFile());
-            } catch (IOException e) {
-                log.error("Failed to disable plugin {}", pluginId, e);
-                return false;
-            }
+    public void disablePlugin(String pluginId) {
+        disabledPlugins.add(pluginId);
+        try {
+            FileUtils.writeLines(disabledPlugins, pluginsRoot.resolve("disabled.txt").toFile());
+        } catch (IOException e) {
+            throw new PluginRuntimeException(e);
         }
-
-        return true;
     }
 
     @Override
-    public boolean enablePlugin(String pluginId) {
-        if (disabledPlugins.remove(pluginId)) {
-            try {
-                FileUtils.writeLines(disabledPlugins, pluginsRoot.resolve("disabled.txt").toFile());
-            } catch (IOException e) {
-                log.error("Failed to enable plugin {}", pluginId, e);
-                return false;
-            }
+    public void enablePlugin(String pluginId) {
+        disabledPlugins.remove(pluginId);
+        try {
+            FileUtils.writeLines(disabledPlugins, pluginsRoot.resolve("disabled.txt").toFile());
+        } catch (IOException e) {
+            throw new PluginRuntimeException(e);
         }
-
-        return true;
     }
 
 }

pf4j/src/main/java/org/pf4j/DependencyResolver.java

@@ -272,7 +272,7 @@ public class DependencyResolver {
     /**
      * It will be thrown if a cyclic dependency is detected.
      */
-    public static class CyclicDependencyException extends PluginException {
+    public static class CyclicDependencyException extends PluginRuntimeException {
 
         public CyclicDependencyException() {
             super("Cyclic dependencies");
@@ -283,7 +283,7 @@ public class DependencyResolver {
     /**
      * Indicates that the dependencies required were not found.
      */
-    public static class DependenciesNotFoundException extends PluginException {
+    public static class DependenciesNotFoundException extends PluginRuntimeException {
 
         private List<String> dependencies;
 
@@ -302,7 +302,7 @@ public class DependencyResolver {
     /**
      * Indicates that some dependencies have wrong version.
      */
-    public static class DependenciesWrongVersionException extends PluginException {
+    public static class DependenciesWrongVersionException extends PluginRuntimeException {
 
         private List<WrongDependencyVersion> dependencies;
 

pf4j/src/main/java/org/pf4j/DevelopmentPluginClasspath.java

@@ -27,7 +27,7 @@ public class DevelopmentPluginClasspath extends PluginClasspath {
      * The development plugin classpath for <a href="https://maven.apache.org">Maven</a>.
      * The classes directory is {@code target/classes} and the lib directory is {@code target/lib}.
      */
-    public static final PluginClasspath MAVEN = new PluginClasspath().addClassesDirectories("target/classes").addLibDirectories("target/lib");
+    public static final PluginClasspath MAVEN = new PluginClasspath().addClassesDirectories("target/classes").addJarsDirectories("target/lib");
 
     /**
      * The development plugin classpath for <a href="https://gradle.org">Gradle</a>.
@@ -46,9 +46,9 @@ public class DevelopmentPluginClasspath extends PluginClasspath {
         addClassesDirectories(GRADLE.getClassesDirectories());
         addClassesDirectories(KOTLIN.getClassesDirectories());
 
-        addLibDirectories(MAVEN.getLibDirectories());
-        addLibDirectories(GRADLE.getLibDirectories());
-        addLibDirectories(KOTLIN.getLibDirectories());
+        addJarsDirectories(MAVEN.getJarsDirectories());
+        addJarsDirectories(GRADLE.getJarsDirectories());
+        addJarsDirectories(KOTLIN.getJarsDirectories());
     }
 
 }

pf4j/src/main/java/org/pf4j/DevelopmentPluginLoader.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+/**
+ * Load all information needed by a plugin from {@link DevelopmentPluginClasspath}.
+ *
+ * @author Decebal Suiu
+ */
+public class DevelopmentPluginLoader extends BasePluginLoader {
+
+    public DevelopmentPluginLoader(PluginManager pluginManager) {
+        super(pluginManager, new DevelopmentPluginClasspath());
+    }
+
+}

pf4j/src/main/java/org/pf4j/DevelopmentPluginRepository.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+import org.pf4j.util.AndFileFilter;
+import org.pf4j.util.DirectoryFileFilter;
+import org.pf4j.util.HiddenFilter;
+import org.pf4j.util.NameFileFilter;
+import org.pf4j.util.NotFileFilter;
+import org.pf4j.util.OrFileFilter;
+
+import java.io.FileFilter;
+import java.nio.file.Path;
+
+/**
+ * @author Decebal Suiu
+ */
+public class DevelopmentPluginRepository extends BasePluginRepository {
+
+    public static final String MAVEN_BUILD_DIR = "target";
+    public static final String GRADLE_BUILD_DIR = "build";
+
+    public DevelopmentPluginRepository(Path pluginsRoot) {
+        super(pluginsRoot);
+
+        AndFileFilter pluginsFilter = new AndFileFilter(new DirectoryFileFilter());
+        pluginsFilter.addFileFilter(new NotFileFilter(createHiddenPluginFilter()));
+        setFilter(pluginsFilter);
+    }
+
+    protected FileFilter createHiddenPluginFilter() {
+        OrFileFilter hiddenPluginFilter = new OrFileFilter(new HiddenFilter());
+
+        // skip default build output folders since these will cause errors in the logs
+        hiddenPluginFilter
+            .addFileFilter(new NameFileFilter(MAVEN_BUILD_DIR))
+            .addFileFilter(new NameFileFilter(GRADLE_BUILD_DIR));
+
+        return hiddenPluginFilter;
+    }
+
+}

pf4j/src/main/java/org/pf4j/ExtensionFactory.java

@@ -20,6 +20,6 @@ package org.pf4j;
  */
 public interface ExtensionFactory {
 
-    Object create(Class<?> extensionClass);
+    <T> T create(Class<T> extensionClass);
 
 }

pf4j/src/main/java/org/pf4j/JarPluginManager.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+import java.nio.file.Path;
+
+/**
+ * It's a {@link PluginManager} that loads each plugin from a {@code jar} file.
+ * Actually, a plugin is a fat jar, a jar which contains classes from all the libraries,
+ * on which your project depends and, of course, the classes of current project.
+ *
+ * @author Decebal Suiu
+ */
+public class JarPluginManager extends DefaultPluginManager {
+
+    public JarPluginManager() {
+        super();
+    }
+
+    public JarPluginManager(Path pluginsRoot) {
+        super(pluginsRoot);
+    }
+
+    @Override
+    protected PluginDescriptorFinder createPluginDescriptorFinder() {
+        return new ManifestPluginDescriptorFinder();
+    }
+
+    @Override
+    protected PluginLoader createPluginLoader() {
+        return new CompoundPluginLoader()
+            .add(new DevelopmentPluginLoader(this), this::isDevelopment)
+            .add(new JarPluginLoader(this), this::isNotDevelopment);
+    }
+
+    @Override
+    protected PluginRepository createPluginRepository() {
+        return new CompoundPluginRepository()
+            .add(new DevelopmentPluginRepository(getPluginsRoot()), this::isDevelopment)
+            .add(new JarPluginRepository(getPluginsRoot()), this::isNotDevelopment);
+    }
+
+}

pf4j/src/main/java/org/pf4j/LegacyExtensionFinder.java

@@ -20,6 +20,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.Reader;
 import java.net.URL;
@@ -81,11 +82,14 @@ public class LegacyExtensionFinder extends AbstractExtensionFinder {
             Set<String> bucket = new HashSet<>();
 
             try {
-                Enumeration<URL> urls = ((PluginClassLoader) plugin.getPluginClassLoader()).findResources(getExtensionsResource());
-                if (urls.hasMoreElements()) {
-                    collectExtensions(urls, bucket);
-                } else {
-                    log.debug("Cannot find '{}'", getExtensionsResource());
+                log.debug("Read '{}'", getExtensionsResource());
+                ClassLoader pluginClassLoader = plugin.getPluginClassLoader();
+                try (InputStream resourceStream = pluginClassLoader.getResourceAsStream(getExtensionsResource())) {
+                    if (resourceStream == null) {
+                        log.debug("Cannot find '{}'", getExtensionsResource());
+                    } else {
+                        collectExtensions(resourceStream, bucket);
+                    }
                 }
 
                 debugExtensions(bucket);
@@ -103,9 +107,13 @@ public class LegacyExtensionFinder extends AbstractExtensionFinder {
         while (urls.hasMoreElements()) {
             URL url = urls.nextElement();
             log.debug("Read '{}'", url.getFile());
-            try (Reader reader = new InputStreamReader(url.openStream(), StandardCharsets.UTF_8)) {
-                LegacyExtensionStorage.read(reader, bucket);
-            }
+            collectExtensions(url.openStream(), bucket);
+        }
+    }
+
+    private void collectExtensions(InputStream inputStream, Set<String> bucket) throws IOException {
+        try (Reader reader = new InputStreamReader(inputStream, StandardCharsets.UTF_8)) {
+            LegacyExtensionStorage.read(reader, bucket);
         }
     }
 

pf4j/src/main/java/org/pf4j/ManifestPluginDescriptorFinder.java

@@ -37,19 +37,28 @@ public class ManifestPluginDescriptorFinder implements PluginDescriptorFinder {
 
     private static final Logger log = LoggerFactory.getLogger(ManifestPluginDescriptorFinder.class);
 
+    public static final String PLUGIN_ID = "Plugin-Id";
+    public static final String PLUGIN_DESCRIPTION = "Plugin-Description";
+    public static final String PLUGIN_CLASS = "Plugin-Class";
+    public static final String PLUGIN_VERSION = "Plugin-Version";
+    public static final String PLUGIN_PROVIDER = "Plugin-Provider";
+    public static final String PLUGIN_DEPENDENCIES = "Plugin-Dependencies";
+    public static final String PLUGIN_REQUIRES = "Plugin-Requires";
+    public static final String PLUGIN_LICENSE = "Plugin-License";
+
     @Override
     public boolean isApplicable(Path pluginPath) {
         return Files.exists(pluginPath) && (Files.isDirectory(pluginPath) || FileUtils.isJarFile(pluginPath));
     }
 
     @Override
-    public PluginDescriptor find(Path pluginPath) throws PluginException {
+    public PluginDescriptor find(Path pluginPath) {
         Manifest manifest = readManifest(pluginPath);
 
         return createPluginDescriptor(manifest);
     }
 
-    protected Manifest readManifest(Path pluginPath) throws PluginException {
+    protected Manifest readManifest(Path pluginPath) {
         if (FileUtils.isJarFile(pluginPath)) {
             try (JarFile jar = new JarFile(pluginPath.toFile())) {
                 Manifest manifest = jar.getManifest();
@@ -57,28 +66,28 @@ public class ManifestPluginDescriptorFinder implements PluginDescriptorFinder {
                     return manifest;
                 }
             } catch (IOException e) {
-                throw new PluginException(e);
+                throw new PluginRuntimeException(e);
             }
         }
 
         Path manifestPath = getManifestPath(pluginPath);
         if (manifestPath == null) {
-            throw new PluginException("Cannot find the manifest path");
+            throw new PluginRuntimeException("Cannot find the manifest path");
         }
 
         log.debug("Lookup plugin descriptor in '{}'", manifestPath);
         if (Files.notExists(manifestPath)) {
-            throw new PluginException("Cannot find '{}' path", manifestPath);
+            throw new PluginRuntimeException("Cannot find '{}' path", manifestPath);
         }
 
         try (InputStream input = Files.newInputStream(manifestPath)) {
             return new Manifest(input);
         } catch (IOException e) {
-            throw new PluginException(e);
+            throw new PluginRuntimeException(e);
         }
     }
 
-    protected Path getManifestPath(Path pluginPath) throws PluginException {
+    protected Path getManifestPath(Path pluginPath) {
         if (Files.isDirectory(pluginPath)) {
             // legacy (the path is something like "classes/META-INF/MANIFEST.MF")
             return FileUtils.findFile(pluginPath,"MANIFEST.MF");
@@ -92,37 +101,37 @@ public class ManifestPluginDescriptorFinder implements PluginDescriptorFinder {
 
         // TODO validate !!!
         Attributes attributes = manifest.getMainAttributes();
-        String id = attributes.getValue("Plugin-Id");
+        String id = attributes.getValue(PLUGIN_ID);
         pluginDescriptor.setPluginId(id);
 
-        String description = attributes.getValue("Plugin-Description");
+        String description = attributes.getValue(PLUGIN_DESCRIPTION);
         if (StringUtils.isNullOrEmpty(description)) {
             pluginDescriptor.setPluginDescription("");
         } else {
             pluginDescriptor.setPluginDescription(description);
         }
 
-        String clazz = attributes.getValue("Plugin-Class");
+        String clazz = attributes.getValue(PLUGIN_CLASS);
         if (StringUtils.isNotNullOrEmpty(clazz)) {
             pluginDescriptor.setPluginClass(clazz);
         }
 
-        String version = attributes.getValue("Plugin-Version");
+        String version = attributes.getValue(PLUGIN_VERSION);
         if (StringUtils.isNotNullOrEmpty(version)) {
             pluginDescriptor.setPluginVersion(version);
         }
 
-        String provider = attributes.getValue("Plugin-Provider");
+        String provider = attributes.getValue(PLUGIN_PROVIDER);
         pluginDescriptor.setProvider(provider);
-        String dependencies = attributes.getValue("Plugin-Dependencies");
+        String dependencies = attributes.getValue(PLUGIN_DEPENDENCIES);
         pluginDescriptor.setDependencies(dependencies);
 
-        String requires = attributes.getValue("Plugin-Requires");
+        String requires = attributes.getValue(PLUGIN_REQUIRES);
         if (StringUtils.isNotNullOrEmpty(requires)) {
             pluginDescriptor.setRequires(requires);
         }
 
-        pluginDescriptor.setLicense(attributes.getValue("Plugin-License"));
+        pluginDescriptor.setLicense(attributes.getValue(PLUGIN_LICENSE));
 
         return pluginDescriptor;
     }

pf4j/src/main/java/org/pf4j/Plugin.java

@@ -60,21 +60,21 @@ public class Plugin {
      * This method is called by the application when the plugin is started.
      * See {@link PluginManager#startPlugin(String)}.
      */
-    public void start() throws PluginException {
+    public void start() {
     }
 
     /**
      * This method is called by the application when the plugin is stopped.
      * See {@link PluginManager#stopPlugin(String)}.
      */
-    public void stop() throws PluginException {
+    public void stop() {
     }
 
     /**
      * This method is called by the application when the plugin is deleted.
      * See {@link PluginManager#deletePlugin(String)}.
      */
-    public void delete() throws PluginException {
+    public void delete() {
     }
 
 }

pf4j/src/main/java/org/pf4j/PluginAlreadyLoadedException.java

@@ -20,7 +20,7 @@ import java.nio.file.Path;
 /**
  * @author Decebal Suiu
  */
-public class PluginAlreadyLoadedException extends PluginException {
+public class PluginAlreadyLoadedException extends PluginRuntimeException {
 
     private final String pluginId;
     private final Path pluginPath;

pf4j/src/main/java/org/pf4j/PluginClasspath.java

@@ -22,14 +22,15 @@ import java.util.Set;
 
 /**
  * The classpath of the plugin.
- * It contains {@code classes} directories and {@code lib} directories (directories that contains jars).
+ * It contains {@code classes} directories (directories that contain classes files)
+ * and {@code jars} directories (directories that contain jars files).
  *
  * @author Decebal Suiu
  */
 public class PluginClasspath {
 
     private Set<String> classesDirectories = new HashSet<>();
-    private Set<String> libDirectories = new HashSet<>();
+    private Set<String> jarsDirectories = new HashSet<>();
 
     public Set<String> getClassesDirectories() {
         return classesDirectories;
@@ -45,16 +46,16 @@ public class PluginClasspath {
         return this;
     }
 
-    public Set<String> getLibDirectories() {
-        return libDirectories;
+    public Set<String> getJarsDirectories() {
+        return jarsDirectories;
     }
 
-    public PluginClasspath addLibDirectories(String... libDirectories) {
-        return addLibDirectories(Arrays.asList(libDirectories));
+    public PluginClasspath addJarsDirectories(String... jarsDirectories) {
+        return addJarsDirectories(Arrays.asList(jarsDirectories));
     }
 
-    public PluginClasspath addLibDirectories(Collection<String> libDirectories) {
-        this.libDirectories.addAll(libDirectories);
+    public PluginClasspath addJarsDirectories(Collection<String> jarsDirectories) {
+        this.jarsDirectories.addAll(jarsDirectories);
 
         return this;
     }

pf4j/src/main/java/org/pf4j/PluginDescriptorFinder.java

@@ -29,12 +29,9 @@ public interface PluginDescriptorFinder {
 
     /**
      * Returns true if this finder is applicable to the given {@link Path}.
-     *
-     * @param pluginPath
-     * @return
      */
     boolean isApplicable(Path pluginPath);
 
-    PluginDescriptor find(Path pluginPath) throws PluginException;
+    PluginDescriptor find(Path pluginPath);
 
 }

pf4j/src/main/java/org/pf4j/PluginManager.java

@@ -69,8 +69,8 @@ public interface PluginManager {
      * Load a plugin.
      *
      * @param pluginPath the plugin location
-     * @return the pluginId of the installed plugin as specified in
-     *     its {@linkplain PluginDescriptor metadata}; or {@code null}
+     * @return the pluginId of the installed plugin as specified in its {@linkplain PluginDescriptor metadata}
+     * @throws PluginRuntimeException if something goes wrong
      */
     String loadPlugin(Path pluginPath);
 
@@ -83,6 +83,7 @@ public interface PluginManager {
      * Start the specified plugin and its dependencies.
      *
      * @return the plugin state
+     * @throws PluginRuntimeException if something goes wrong
      */
     PluginState startPlugin(String pluginId);
 
@@ -95,6 +96,7 @@ public interface PluginManager {
      * Stop the specified plugin and its dependencies.
      *
      * @return the plugin state
+     * @throws PluginRuntimeException if something goes wrong
      */
     PluginState stopPlugin(String pluginId);
 
@@ -103,6 +105,7 @@ public interface PluginManager {
      *
      * @param pluginId the unique plugin identifier, specified in its metadata
      * @return true if the plugin was unloaded
+     * @throws PluginRuntimeException if something goes wrong
      */
     boolean unloadPlugin(String pluginId);
 
@@ -111,6 +114,7 @@ public interface PluginManager {
      *
      * @param pluginId the unique plugin identifier, specified in its metadata
      * @return true if plugin is disabled
+     * @throws PluginRuntimeException if something goes wrong
      */
     boolean disablePlugin(String pluginId);
 
@@ -119,6 +123,7 @@ public interface PluginManager {
      *
      * @param pluginId the unique plugin identifier, specified in its metadata
      * @return true if plugin is enabled
+     * @throws PluginRuntimeException if something goes wrong
      */
     boolean enablePlugin(String pluginId);
 
@@ -127,6 +132,7 @@ public interface PluginManager {
      *
      * @param pluginId the unique plugin identifier, specified in its metadata
      * @return true if the plugin was deleted
+     * @throws PluginRuntimeException if something goes wrong
      */
     boolean deletePlugin(String pluginId);
 
@@ -134,9 +140,9 @@ public interface PluginManager {
 
     List<Class<?>> getExtensionClasses(String pluginId);
 
-    <T> List<Class<T>> getExtensionClasses(Class<T> type);
+    <T> List<Class<? extends T>> getExtensionClasses(Class<T> type);
 
-    <T> List<Class<T>> getExtensionClasses(Class<T> type, String pluginId);
+    <T> List<Class<? extends T>> getExtensionClasses(Class<T> type, String pluginId);
 
     <T> List<T> getExtensions(Class<T> type);
 
@@ -153,6 +159,20 @@ public interface PluginManager {
      */
     RuntimeMode getRuntimeMode();
 
+    /**
+     * Returns {@code true} if the runtime mode is {@code RuntimeMode.DEVELOPMENT}.
+     */
+    default boolean isDevelopment() {
+        return RuntimeMode.DEVELOPMENT.equals(getRuntimeMode());
+    }
+
+    /**
+     * Returns {@code true} if the runtime mode is not {@code RuntimeMode.DEVELOPMENT}.
+     */
+    default boolean isNotDevelopment() {
+        return !isDevelopment();
+    }
+
     /**
      * Retrieves the {@link PluginWrapper} that loaded the given class 'clazz'.
      */
@@ -180,7 +200,8 @@ public interface PluginManager {
     String getSystemVersion();
 
     /**
-     * Gets the path of the folder where plugins are installed
+     * Gets the path of the folder where plugins are installed.
+     *
      * @return Path of plugins root
      */
     Path getPluginsRoot();

pf4j/src/main/java/org/pf4j/PluginRepository.java

@@ -19,7 +19,7 @@ import java.nio.file.Path;
 import java.util.List;
 
 /**
- * Directory that contains plugins. A plugin could be a zip file.
+ * Directory that contains plugins. A plugin could be a {@code directory}, @code zip} or {@code jar} file.
  *
  * @author Decebal Suiu
  * @author Mário Franco
@@ -29,7 +29,7 @@ public interface PluginRepository {
     /**
      * List all plugin paths.
      *
-     * @return a list of files
+     * @return a list with paths
      */
     List<Path> getPluginPaths();
 
@@ -38,6 +38,7 @@ public interface PluginRepository {
      *
      * @param pluginPath the plugin path
      * @return true if deleted
+     * @throws PluginRuntimeException if something goes wrong
      */
     boolean deletePluginPath(Path pluginPath);
 

pf4j/src/main/java/org/pf4j/PluginException.java → pf4j/src/main/java/org/pf4j/PluginRuntimeException.java

@@ -23,29 +23,25 @@ import org.pf4j.util.StringUtils;
  *
  * @author Decebal Suiu
  */
-public class PluginException extends Exception {
+public class PluginRuntimeException extends RuntimeException {
 
-    public PluginException() {
+    public PluginRuntimeException() {
         super();
     }
 
-    public PluginException(String message) {
+    public PluginRuntimeException(String message) {
         super(message);
     }
 
-    public PluginException(Throwable cause) {
+    public PluginRuntimeException(Throwable cause) {
         super(cause);
     }
 
-    public PluginException(String message, Throwable cause) {
-        super(message, cause);
-    }
-
-    public PluginException(Throwable cause, String message, Object... args) {
+    public PluginRuntimeException(Throwable cause, String message, Object... args) {
         super(StringUtils.format(message, args), cause);
     }
 
-    public PluginException(String message, Object... args) {
+    public PluginRuntimeException(String message, Object... args) {
         super(StringUtils.format(message, args));
     }
 

pf4j/src/main/java/org/pf4j/PluginStatusProvider.java

@@ -33,16 +33,16 @@ public interface PluginStatusProvider {
      * Disables a plugin from being loaded.
      *
      * @param pluginId the unique plugin identifier, specified in its metadata
-     * @return true if plugin is disabled
+     * @throws PluginRuntimeException if something goes wrong
      */
-    boolean disablePlugin(String pluginId);
+    void disablePlugin(String pluginId);
 
     /**
      * Enables a plugin that has previously been disabled.
      *
      * @param pluginId the unique plugin identifier, specified in its metadata
-     * @return true if plugin is enabled
+     * @throws PluginRuntimeException if something goes wrong
      */
-    boolean enablePlugin(String pluginId);
+    void enablePlugin(String pluginId);
 
 }

pf4j/src/main/java/org/pf4j/PluginWrapper.java

@@ -41,6 +41,7 @@ public class PluginWrapper {
         this.pluginClassLoader = pluginClassLoader;
 
         pluginState = PluginState.CREATED;
+        runtimeMode = pluginManager.getRuntimeMode();
     }
 
     /**
@@ -120,11 +121,9 @@ public class PluginWrapper {
         }
 
         PluginWrapper other = (PluginWrapper) obj;
-        if (!descriptor.getPluginId().equals(other.descriptor.getPluginId())) {
-            return false;
-        }
 
-        return true;
+        return descriptor.getPluginId().equals(other.descriptor.getPluginId());
+
     }
 
     @Override
@@ -136,10 +135,6 @@ public class PluginWrapper {
         this.pluginState = pluginState;
     }
 
-    void setRuntimeMode(RuntimeMode runtimeMode) {
-        this.runtimeMode = runtimeMode;
-    }
-
     void setPluginFactory(PluginFactory pluginFactory) {
         this.pluginFactory = pluginFactory;
     }

pf4j/src/main/java/org/pf4j/PropertiesPluginDescriptorFinder.java

@@ -36,7 +36,16 @@ public class PropertiesPluginDescriptorFinder implements PluginDescriptorFinder
 
     private static final Logger log = LoggerFactory.getLogger(PropertiesPluginDescriptorFinder.class);
 
-    private static final String DEFAULT_PROPERTIES_FILE_NAME = "plugin.properties";
+    public static final String DEFAULT_PROPERTIES_FILE_NAME = "plugin.properties";
+
+    public static final String PLUGIN_ID = "plugin.id";
+    public static final String PLUGIN_DESCRIPTION = "plugin.description";
+    public static final String PLUGIN_CLASS = "plugin.class";
+    public static final String PLUGIN_VERSION = "plugin.version";
+    public static final String PLUGIN_PROVIDER = "plugin.provider";
+    public static final String PLUGIN_DEPENDENCIES = "plugin.dependencies";
+    public static final String PLUGIN_REQUIRES = "plugin.requires";
+    public static final String PLUGIN_LICENSE = "plugin.license";
 
     protected String propertiesFileName;
 
@@ -54,34 +63,34 @@ public class PropertiesPluginDescriptorFinder implements PluginDescriptorFinder
     }
 
     @Override
-    public PluginDescriptor find(Path pluginPath) throws PluginException {
+    public PluginDescriptor find(Path pluginPath) {
         Properties properties = readProperties(pluginPath);
 
         return createPluginDescriptor(properties);
     }
 
-    protected Properties readProperties(Path pluginPath) throws PluginException {
+    protected Properties readProperties(Path pluginPath) {
         Path propertiesPath = getPropertiesPath(pluginPath, propertiesFileName);
         if (propertiesPath == null) {
-            throw new PluginException("Cannot find the properties path");
+            throw new PluginRuntimeException("Cannot find the properties path");
         }
 
         log.debug("Lookup plugin descriptor in '{}'", propertiesPath);
         if (Files.notExists(propertiesPath)) {
-            throw new PluginException("Cannot find '{}' path", propertiesPath);
+            throw new PluginRuntimeException("Cannot find '{}' path", propertiesPath);
         }
 
         Properties properties = new Properties();
         try (InputStream input = Files.newInputStream(propertiesPath)) {
             properties.load(input);
         } catch (IOException e) {
-            throw new PluginException(e);
+            throw new PluginRuntimeException(e);
         }
 
         return properties;
     }
 
-    protected Path getPropertiesPath(Path pluginPath, String propertiesFileName) throws PluginException {
+    protected Path getPropertiesPath(Path pluginPath, String propertiesFileName) {
         if (Files.isDirectory(pluginPath)) {
             return pluginPath.resolve(Paths.get(propertiesFileName));
         } else {
@@ -89,7 +98,7 @@ public class PropertiesPluginDescriptorFinder implements PluginDescriptorFinder
             try {
                 return FileUtils.getPath(pluginPath, propertiesFileName);
             } catch (IOException e) {
-                throw new PluginException(e);
+                throw new PluginRuntimeException(e);
             }
         }
     }
@@ -98,38 +107,38 @@ public class PropertiesPluginDescriptorFinder implements PluginDescriptorFinder
         DefaultPluginDescriptor pluginDescriptor = createPluginDescriptorInstance();
 
         // TODO validate !!!
-        String id = properties.getProperty("plugin.id");
+        String id = properties.getProperty(PLUGIN_ID);
         pluginDescriptor.setPluginId(id);
 
-        String description = properties.getProperty("plugin.description");
+        String description = properties.getProperty(PLUGIN_DESCRIPTION);
         if (StringUtils.isNullOrEmpty(description)) {
             pluginDescriptor.setPluginDescription("");
         } else {
             pluginDescriptor.setPluginDescription(description);
         }
 
-        String clazz = properties.getProperty("plugin.class");
+        String clazz = properties.getProperty(PLUGIN_CLASS);
         if (StringUtils.isNotNullOrEmpty(clazz)) {
             pluginDescriptor.setPluginClass(clazz);
         }
 
-        String version = properties.getProperty("plugin.version");
+        String version = properties.getProperty(PLUGIN_VERSION);
         if (StringUtils.isNotNullOrEmpty(version)) {
             pluginDescriptor.setPluginVersion(version);
         }
 
-        String provider = properties.getProperty("plugin.provider");
+        String provider = properties.getProperty(PLUGIN_PROVIDER);
         pluginDescriptor.setProvider(provider);
 
-        String dependencies = properties.getProperty("plugin.dependencies");
+        String dependencies = properties.getProperty(PLUGIN_DEPENDENCIES);
         pluginDescriptor.setDependencies(dependencies);
 
-        String requires = properties.getProperty("plugin.requires");
+        String requires = properties.getProperty(PLUGIN_REQUIRES);
         if (StringUtils.isNotNullOrEmpty(requires)) {
             pluginDescriptor.setRequires(requires);
         }
 
-        pluginDescriptor.setLicense(properties.getProperty("plugin.license"));
+        pluginDescriptor.setLicense(properties.getProperty(PLUGIN_LICENSE));
 
         return pluginDescriptor;
     }

pf4j/src/main/java/org/pf4j/RuntimeMode.java

@@ -41,7 +41,7 @@ public enum RuntimeMode {
         }
     }
 
-    private RuntimeMode(final String name, final String... aliases) {
+    RuntimeMode(final String name, final String... aliases) {
         this.name = name;
         this.aliases = aliases;
     }

pf4j/src/main/java/org/pf4j/SingletonExtensionFactory.java

@@ -39,13 +39,14 @@ public class SingletonExtensionFactory extends DefaultExtensionFactory {
     }
 
     @Override
-    public Object create(Class<?> extensionClass) {
+    @SuppressWarnings("unchecked")
+    public <T> T create(Class<T> extensionClass) {
         String extensionClassName = extensionClass.getName();
         if (cache.containsKey(extensionClassName)) {
-            return cache.get(extensionClassName);
+            return (T) cache.get(extensionClassName);
         }
 
-        Object extension = super.create(extensionClass);
+        T extension = super.create(extensionClass);
         if (extensionClassNames.isEmpty() || extensionClassNames.contains(extensionClassName)) {
             cache.put(extensionClassName, extension);
         }

pf4j/src/main/java/org/pf4j/ZipPluginManager.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+/**
+ * It's a {@link PluginManager} that loads each plugin from a {@code zip} file.
+ * The structure of the zip file is:
+ * <ul>
+ * <li>{@code lib} directory that contains all dependencies (as jar files); it's optional (no dependencies)
+ * <li>{@code classes} directory that contains all plugin's classes
+ * </ul>
+ *
+ * @author Decebal Suiu
+ */
+public class ZipPluginManager extends DefaultPluginManager {
+
+    @Override
+    protected PluginDescriptorFinder createPluginDescriptorFinder() {
+        return new PropertiesPluginDescriptorFinder();
+    }
+
+    @Override
+    protected PluginLoader createPluginLoader() {
+        return new CompoundPluginLoader()
+            .add(new DevelopmentPluginLoader(this), this::isDevelopment)
+            .add(new DefaultPluginLoader(this), this::isNotDevelopment);
+    }
+
+    @Override
+    protected PluginRepository createPluginRepository() {
+        return new CompoundPluginRepository()
+            .add(new DevelopmentPluginRepository(getPluginsRoot()), this::isDevelopment)
+            .add(new DefaultPluginRepository(getPluginsRoot()), this::isNotDevelopment);
+    }
+
+}

pf4j/src/main/java/org/pf4j/processor/ExtensionAnnotationProcessor.java

@@ -109,11 +109,7 @@ public class ExtensionAnnotationProcessor extends AbstractProcessor {
             String extension = getBinaryName(extensionElement);
             for (TypeElement extensionPointElement : extensionPointElements) {
                 String extensionPoint = getBinaryName(extensionPointElement);
-                Set<String> extensionPoints = extensions.get(extensionPoint);
-                if (extensionPoints == null) {
-                    extensionPoints = new TreeSet<>();
-                    extensions.put(extensionPoint, extensionPoints);
-                }
+                Set<String> extensionPoints = extensions.computeIfAbsent(extensionPoint, k -> new TreeSet<>());
                 extensionPoints.add(extension);
             }
         }

pf4j/src/main/java/org/pf4j/util/AndFileFilter.java

@@ -23,11 +23,9 @@ import java.util.Collections;
 import java.util.List;
 
 /**
- * This filter providing conditional AND logic across a list of
- * file filters. This filter returns <code>true</code> if all filters in the
- * list return <code>true</code>. Otherwise, it returns <code>false</code>.
- * Checking of the file filter list stops when the first filter returns
- * <code>false</code>.
+ * This filter providing conditional AND logic across a list of file filters.
+ * This filter returns {@code true} if all filters in the list return {@code true}. Otherwise, it returns {@code false}.
+ * Checking of the file filter list stops when the first filter returns {@code false}.
  *
  * @author Decebal Suiu
  */
@@ -37,7 +35,7 @@ public class AndFileFilter implements FileFilter {
     private List<FileFilter> fileFilters;
 
     public AndFileFilter() {
-        this(new ArrayList<FileFilter>());
+        this(new ArrayList<>());
     }
 
     public AndFileFilter(FileFilter... fileFilters) {
@@ -68,7 +66,7 @@ public class AndFileFilter implements FileFilter {
 
     @Override
     public boolean accept(File file) {
-        if (this.fileFilters.size() == 0) {
+        if (this.fileFilters.isEmpty()) {
             return false;
         }
 

pf4j/src/main/java/org/pf4j/util/DirectedGraph.java

@@ -44,7 +44,7 @@ public class DirectedGraph<V> {
             return;
         }
 
-        neighbors.put(vertex, new ArrayList<V>());
+        neighbors.put(vertex, new ArrayList<>());
     }
 
     /**
@@ -85,7 +85,7 @@ public class DirectedGraph<V> {
     }
 
     public List<V> getNeighbors(V vertex) {
-        return containsVertex(vertex) ? neighbors.get(vertex) : new ArrayList<V>();
+        return containsVertex(vertex) ? neighbors.get(vertex) : new ArrayList<>();
     }
 
     /**
@@ -101,7 +101,7 @@ public class DirectedGraph<V> {
     }
 
     /**
-     * Report (as a Map) the in-degree (the number of head ends adjacent to a vertex) of each vertex.
+     * Report (as a {@link Map}) the in-degree (the number of head ends adjacent to a vertex) of each vertex.
      */
     public Map<V, Integer> inDegree() {
         Map<V, Integer> result = new HashMap<>();
@@ -181,9 +181,9 @@ public class DirectedGraph<V> {
      */
     @Override
     public String toString() {
-        StringBuffer sb = new StringBuffer();
+        StringBuilder sb = new StringBuilder();
         for (V vertex : neighbors.keySet()) {
-            sb.append("\n   " + vertex + " -> " + neighbors.get(vertex));
+            sb.append("\n   ").append(vertex).append(" -> ").append(neighbors.get(vertex));
         }
 
         return sb.toString();

pf4j/src/main/java/org/pf4j/util/FileUtils.java

@@ -172,17 +172,10 @@ public class FileUtils {
 
         FileTime pluginZipDate = Files.getLastModifiedTime(filePath);
         String fileName = filePath.getFileName().toString();
-        Path pluginDirectory = filePath.resolveSibling(fileName.substring(0, fileName.lastIndexOf(".")));
+        String directoryName = fileName.substring(0, fileName.lastIndexOf("."));
+        Path pluginDirectory = filePath.resolveSibling(directoryName);
 
         if (!Files.exists(pluginDirectory) || pluginZipDate.compareTo(Files.getLastModifiedTime(pluginDirectory)) > 0) {
-            // do not overwrite an old version, remove it
-            if (Files.exists(pluginDirectory)) {
-                FileUtils.delete(pluginDirectory);
-            }
-
-            // create root for plugin
-            Files.createDirectories(pluginDirectory);
-
             // expand '.zip' file
             Unzip unzip = new Unzip();
             unzip.setSource(filePath.toFile());

pf4j/src/main/java/org/pf4j/util/OrFileFilter.java

@@ -23,11 +23,9 @@ import java.util.Collections;
 import java.util.List;
 
 /**
- * This filter providing conditional OR logic across a list of
- * file filters. This filter returns <code>true</code> if one filter in the
- * list return <code>true</code>. Otherwise, it returns <code>false</code>.
- * Checking of the file filter list stops when the first filter returns
- * <code>true</code>.
+ * This filter providing conditional OR logic across a list of file filters.
+ * This filter returns {@code true} if one filter in the list return {@code true}. Otherwise, it returns {@code false}.
+ * Checking of the file filter list stops when the first filter returns {@code true}.
  *
  * @author Decebal Suiu
  */
@@ -37,7 +35,7 @@ public class OrFileFilter implements FileFilter {
     private List<FileFilter> fileFilters;
 
     public OrFileFilter() {
-        this(new ArrayList<FileFilter>());
+        this(new ArrayList<>());
     }
 
     public OrFileFilter(FileFilter... fileFilters) {
@@ -68,7 +66,7 @@ public class OrFileFilter implements FileFilter {
 
     @Override
     public boolean accept(File file) {
-        if (this.fileFilters.size() == 0) {
+        if (this.fileFilters.isEmpty()) {
             return true;
         }
 

pf4j/src/main/java/org/pf4j/util/Unzip.java

@@ -63,10 +63,14 @@ public class Unzip {
         this.destination = destination;
     }
 
+    /**
+     * Extract the content of zip file ({@code source}) to destination directory.
+     * If destination directory already exists it will be deleted before.
+     */
     public void extract() throws IOException {
         log.debug("Extract content of '{}' to '{}'", source, destination);
 
-        // delete destination file if exists
+        // delete destination directory if exists
         if (destination.exists() && destination.isDirectory()) {
             FileUtils.delete(destination.toPath());
         }

pf4j/src/test/java/org/pf4j/AbstractExtensionFinderTest.java

@@ -15,9 +15,9 @@
  */
 package org.pf4j;
 
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 import org.pf4j.plugin.FailTestPlugin;
 import org.pf4j.plugin.TestExtensionPoint;
 
@@ -28,7 +28,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.Mockito.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
@@ -40,7 +40,7 @@ public class AbstractExtensionFinderTest {
 
     private PluginManager pluginManager;
 
-    @Before
+    @BeforeEach
     public void setUp() {
         PluginWrapper pluginStarted = mock(PluginWrapper.class);
         when(pluginStarted.getPluginClassLoader()).thenReturn(getClass().getClassLoader());
@@ -57,7 +57,7 @@ public class AbstractExtensionFinderTest {
         when(pluginManager.getExtensionFactory()).thenReturn(new DefaultExtensionFactory());
     }
 
-    @After
+    @AfterEach
     public void tearDown() {
         pluginManager = null;
     }

pf4j/src/test/java/org/pf4j/AbstractPluginManagerTest.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+import org.junit.jupiter.api.Test;
+import org.pf4j.plugin.TestExtension;
+import org.pf4j.plugin.TestExtensionPoint;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.CALLS_REAL_METHODS;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+/**
+ * @author Decebal Suiu
+ */
+public class AbstractPluginManagerTest {
+
+    @Test
+    public void getExtensionsByType() {
+        AbstractPluginManager pluginManager = mock(AbstractPluginManager.class, CALLS_REAL_METHODS);
+
+        ExtensionFinder extensionFinder = mock(ExtensionFinder.class);
+        List<ExtensionWrapper<TestExtensionPoint>> extensionList = new ArrayList<>(1);
+        extensionList.add(new ExtensionWrapper<>(new ExtensionDescriptor(0, TestExtension.class), new DefaultExtensionFactory()));
+        when(extensionFinder.find(TestExtensionPoint.class)).thenReturn(extensionList);
+
+        pluginManager.extensionFinder = extensionFinder;
+        List<TestExtensionPoint> extensions = pluginManager.getExtensions(TestExtensionPoint.class);
+        assertEquals(1, extensions.size());
+    }
+
+}

pf4j/src/test/java/org/pf4j/CompoundPluginDescriptorFinderTest.java

@@ -15,28 +15,34 @@
  */
 package org.pf4j;
 
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.pf4j.plugin.PluginJar;
 import org.pf4j.plugin.PluginZip;
+import org.pf4j.plugin.TestPlugin;
 
-import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Arrays;
-import java.util.List;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Properties;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 /**
  * @author Decebal Suiu
  */
 public class CompoundPluginDescriptorFinderTest {
 
-    @Rule
-    public TemporaryFolder pluginsFolder = new TemporaryFolder();
+    @TempDir
+    Path pluginsPath;
 
     @Test
     public void add() {
@@ -49,8 +55,8 @@ public class CompoundPluginDescriptorFinderTest {
 
     @Test
     public void find() throws Exception {
-        Path pluginPath = pluginsFolder.newFolder("test-plugin-1").toPath();
-        Files.write(pluginPath.resolve("plugin.properties"), getPlugin1Properties(), StandardCharsets.UTF_8);
+        Path pluginPath = Files.createDirectories(pluginsPath.resolve("test-plugin-1"));
+        storePropertiesToPath(getPlugin1Properties(), pluginPath);
 
         PluginDescriptorFinder descriptorFinder = new CompoundPluginDescriptorFinder()
             .add(new PropertiesPluginDescriptorFinder());
@@ -64,31 +70,32 @@ public class CompoundPluginDescriptorFinderTest {
     @Test
     public void findInJar() throws Exception {
         PluginDescriptorFinder descriptorFinder = new CompoundPluginDescriptorFinder()
-            .add(new PropertiesPluginDescriptorFinder());
+            .add(new ManifestPluginDescriptorFinder());
 
-        PluginZip pluginJar = new PluginZip.Builder(pluginsFolder.newFile("my-plugin-1.2.3.jar"), "myPlugin")
+        PluginJar pluginJar = new PluginJar.Builder(pluginsPath.resolve("my-plugin-1.2.3.jar"), "myPlugin")
+            .pluginClass(TestPlugin.class.getName())
             .pluginVersion("1.2.3")
             .build();
 
         PluginDescriptor pluginDescriptor = descriptorFinder.find(pluginJar.path());
         assertNotNull(pluginDescriptor);
         assertEquals("myPlugin", pluginJar.pluginId());
+        assertEquals(TestPlugin.class.getName(), pluginJar.pluginClass());
         assertEquals("1.2.3", pluginJar.pluginVersion());
     }
 
-    @Test(expected = PluginException.class)
-    public void testNotFound() throws Exception {
+    @Test
+    public void testNotFound() {
         PluginDescriptorFinder descriptorFinder = new CompoundPluginDescriptorFinder();
-        Path pluginsPath = pluginsFolder.getRoot().toPath();
-        descriptorFinder.find(pluginsPath.resolve("test-plugin-3"));
+        assertThrows(PluginRuntimeException.class, () -> descriptorFinder.find(pluginsPath.resolve("test-plugin-3")));
     }
 
     @Test
     public void testSpaceCharacterInFileName() throws Exception {
-        PluginDescriptorFinder descriptorFinder = new PropertiesPluginDescriptorFinder();
-        File jar = pluginsFolder.newFile("my plugin-1.2.3.jar");
+        PluginDescriptorFinder descriptorFinder = new CompoundPluginDescriptorFinder()
+            .add(new ManifestPluginDescriptorFinder());
 
-        PluginZip pluginJar = new PluginZip.Builder(jar, "myPlugin")
+        PluginJar pluginJar = new PluginJar.Builder(pluginsPath.resolve("my plugin-1.2.3.jar"), "myPlugin")
             .pluginVersion("1.2.3")
             .build();
 
@@ -96,21 +103,24 @@ public class CompoundPluginDescriptorFinderTest {
         assertNotNull(pluginDescriptor);
     }
 
-    private List<String> getPlugin1Properties() {
-        String[] lines = new String[] {
-            "plugin.id=test-plugin-1\n"
-            + "plugin.version=0.0.1\n"
-            + "plugin.description=Test Plugin 1\n"
-            + "plugin.provider=Decebal Suiu\n"
-            + "plugin.class=org.pf4j.plugin.TestPlugin\n"
-            + "plugin.dependencies=test-plugin-2,test-plugin-3@~1.0\n"
-            + "plugin.requires=>=1\n"
-            + "plugin.license=Apache-2.0\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private Properties getPlugin1Properties() {
+        Map<String, String> map = new LinkedHashMap<>(7);
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_ID, "test-plugin-1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_CLASS, TestPlugin.class.getName());
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_VERSION, "0.0.1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_DEPENDENCIES, "test-plugin-2,test-plugin-3@~1.0");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_REQUIRES, ">=1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_LICENSE, "Apache-2.0");
+
+        return PluginZip.createProperties(map);
+    }
+
+    private void storePropertiesToPath(Properties properties, Path pluginPath) throws IOException {
+        Path path = pluginPath.resolve(PropertiesPluginDescriptorFinder.DEFAULT_PROPERTIES_FILE_NAME);
+        try (Writer writer = new OutputStreamWriter(new FileOutputStream(path.toFile()), StandardCharsets.UTF_8)) {
+            properties.store(writer, "");
+        }
     }
 
 }

pf4j/src/test/java/org/pf4j/DefaultExtensionFactoryTest.java

@@ -15,26 +15,38 @@
  */
 package org.pf4j;
 
-import org.junit.Test;
-import org.pf4j.plugin.TestExtension;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 import org.pf4j.plugin.FailTestExtension;
+import org.pf4j.plugin.TestExtension;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 /**
- *
  * @author Mario Franco
  */
 public class DefaultExtensionFactoryTest {
 
+    private ExtensionFactory extensionFactory;
+
+    @BeforeEach
+    public void setUp() {
+        extensionFactory = new DefaultExtensionFactory();
+    }
+
+    @AfterEach
+    public void tearDown() {
+        extensionFactory = null;
+    }
+
     /**
      * Test of create method, of class DefaultExtensionFactory.
      */
     @Test
     public void testCreate() {
-        DefaultExtensionFactory instance = new DefaultExtensionFactory();
-        Object result = instance.create(TestExtension.class);
-        assertNotNull(result);
+        assertNotNull(extensionFactory.create(TestExtension.class));
     }
 
     /**
@@ -42,9 +54,7 @@ public class DefaultExtensionFactoryTest {
      */
     @Test
     public void testCreateFailConstructor() {
-        DefaultExtensionFactory instance = new DefaultExtensionFactory();
-        Object result = instance.create(FailTestExtension.class);
-        assertNull(result);
+        assertThrows(PluginRuntimeException.class, () -> extensionFactory.create(FailTestExtension.class));
     }
 
 }

pf4j/src/test/java/org/pf4j/DefaultPluginFactoryTest.java

@@ -15,15 +15,15 @@
  */
 package org.pf4j;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.pf4j.plugin.AnotherFailTestPlugin;
 import org.pf4j.plugin.FailTestPlugin;
 import org.pf4j.plugin.TestPlugin;
 
 import static org.hamcrest.CoreMatchers.instanceOf;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertThat;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 

pf4j/src/test/java/org/pf4j/DefaultPluginManagerTest.java

@@ -15,21 +15,21 @@
  */
 package org.pf4j;
 
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.pf4j.plugin.PluginZip;
 
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
@@ -38,14 +38,12 @@ public class DefaultPluginManagerTest {
     private DefaultPluginManager pluginManager;
     private DefaultPluginDescriptor pluginDescriptor;
     private PluginWrapper pluginWrapper;
-    private Path pluginsPath;
 
-    @Rule
-    public TemporaryFolder pluginsFolder = new TemporaryFolder();
+    @TempDir
+    Path pluginsPath;
 
-    @Before
+    @BeforeEach
     public void setUp() throws IOException {
-        pluginsPath = pluginsFolder.getRoot().toPath();
         pluginManager = new DefaultPluginManager(pluginsPath);
 
         pluginDescriptor = new DefaultPluginDescriptor();
@@ -59,7 +57,7 @@ public class DefaultPluginManagerTest {
         pluginWrapper = new PluginWrapper(pluginManager, pluginDescriptor, Files.createTempDirectory("test"), getClass().getClassLoader());
     }
 
-    @After
+    @AfterEach
     public void tearDown() {
         pluginManager = null;
         pluginDescriptor = null;
@@ -67,24 +65,24 @@ public class DefaultPluginManagerTest {
     }
 
     @Test
-    public void validateOK() throws PluginException {
+    public void validateOK() {
         pluginManager.validatePluginDescriptor(pluginDescriptor);
     }
 
-    @Test(expected = PluginException.class)
-    public void validateFailsOnId() throws PluginException {
+    @Test
+    public void validateFailsOnId() {
         pluginDescriptor.setPluginId("");
-        pluginManager.validatePluginDescriptor(pluginDescriptor);
+        assertThrows(PluginRuntimeException.class, () -> pluginManager.validatePluginDescriptor(pluginDescriptor));
     }
 
-    @Test(expected = PluginException.class)
-    public void validateFailsOnVersion() throws PluginException {
+    @Test
+    public void validateFailsOnVersion() {
         pluginDescriptor.setPluginVersion(null);
-        pluginManager.validatePluginDescriptor(pluginDescriptor);
+        assertThrows(PluginRuntimeException.class, () -> pluginManager.validatePluginDescriptor(pluginDescriptor));
     }
 
     @Test
-    public void validateNoPluginClass() throws PluginException {
+    public void validateNoPluginClass() {
         pluginManager.validatePluginDescriptor(pluginDescriptor);
         assertEquals(Plugin.class.getName(), pluginDescriptor.getPluginClass());
     }
@@ -132,7 +130,7 @@ public class DefaultPluginManagerTest {
      */
     @Test
     public void testPluginDisabledNoStart() throws IOException {
-        new PluginZip.Builder(pluginsFolder.newFile("my-plugin-1.2.3.zip"), "myPlugin")
+        new PluginZip.Builder(pluginsPath.resolve("my-plugin-1.2.3.zip"), "myPlugin")
             .pluginVersion("1.2.3")
             .build();
 

pf4j/src/test/java/org/pf4j/DefaultPluginRepositoryTest.java

@@ -15,20 +15,18 @@
  */
 package org.pf4j;
 
-import org.junit.Before;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.util.List;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Mario Franco
@@ -36,25 +34,18 @@ import static org.junit.Assert.assertTrue;
  */
 public class DefaultPluginRepositoryTest {
 
-    private Path pluginsPath;
+    @TempDir
+    Path pluginsPath;
 
-    @Rule
-    public TemporaryFolder pluginsFolder = new TemporaryFolder();
-
-    @Before
+    @BeforeEach
     public void setUp() throws IOException {
-        pluginsPath = pluginsFolder.getRoot().toPath();
-
-        pluginsFolder.newFolder("plugin-1");
+        Path plugin1Path = Files.createDirectory(pluginsPath.resolve("plugin-1"));
         // Prove that we can delete a folder with a file inside
-        Files.createFile(Paths.get(pluginsFolder.getRoot().getAbsolutePath()).resolve("plugin-1").resolve("myfile"));
+        Files.createFile(plugin1Path.resolve("myfile"));
         // Create a zip file for plugin-1 to test that it is deleted when plugin is deleted
-        Files.createFile(Paths.get(pluginsFolder.getRoot().getAbsolutePath()).resolve("plugin-1.zip"));
-        pluginsFolder.newFolder("plugin-2");
-        pluginsFolder.newFolder("plugin-3");
-        // standard maven/gradle bin folder - these should be skipped in development mode because the cause errors
-        pluginsFolder.newFolder("target");
-        pluginsFolder.newFolder("build");
+        Files.createFile(pluginsPath.resolve("plugin-1.zip"));
+        Files.createDirectory(pluginsPath.resolve("plugin-2"));
+        Files.createDirectory(pluginsPath.resolve("plugin-3"));
     }
 
     /**
@@ -62,29 +53,14 @@ public class DefaultPluginRepositoryTest {
      */
     @Test
     public void testGetPluginArchives() {
-        PluginRepository repository = new DefaultPluginRepository(pluginsPath, false);
+        PluginRepository repository = new DefaultPluginRepository(pluginsPath);
 
         List<Path> pluginPaths = repository.getPluginPaths();
 
-        assertEquals(5, pluginPaths.size());
+        assertEquals(3, pluginPaths.size());
         assertPathExists(pluginPaths, pluginsPath.resolve("plugin-1"));
         assertPathExists(pluginPaths, pluginsPath.resolve("plugin-2"));
         assertPathExists(pluginPaths, pluginsPath.resolve("plugin-3"));
-        // when not in development mode we will honor these folders
-        assertPathExists(pluginPaths, pluginsPath.resolve("target"));
-        assertPathExists(pluginPaths, pluginsPath.resolve("build"));
-    }
-
-    @Test
-    public void testGetPluginArchivesInDevelopmentMode() {
-        PluginRepository repository = new DefaultPluginRepository(pluginsPath, true);
-
-        List<Path> pluginPaths = repository.getPluginPaths();
-
-        // target and build should be ignored
-        assertEquals(3, pluginPaths.size());
-        assertPathDoesNotExists(pluginPaths, pluginsPath.resolve("target"));
-        assertPathDoesNotExists(pluginPaths, pluginsPath.resolve("build"));
     }
 
     /**
@@ -92,15 +68,13 @@ public class DefaultPluginRepositoryTest {
      */
     @Test
     public void testDeletePluginPath() {
-        PluginRepository repository = new DefaultPluginRepository(pluginsPath, false);
+        PluginRepository repository = new DefaultPluginRepository(pluginsPath);
 
         assertTrue(Files.exists(pluginsPath.resolve("plugin-1.zip")));
         assertTrue(repository.deletePluginPath(pluginsPath.resolve("plugin-1")));
         assertFalse(Files.exists(pluginsPath.resolve("plugin-1.zip")));
         assertTrue(repository.deletePluginPath(pluginsPath.resolve("plugin-3")));
         assertFalse(repository.deletePluginPath(pluginsPath.resolve("plugin-4")));
-        assertTrue(repository.deletePluginPath(pluginsPath.resolve("target")));
-        assertTrue(repository.deletePluginPath(pluginsPath.resolve("build")));
 
         List<Path> pluginPaths = repository.getPluginPaths();
 
@@ -109,11 +83,7 @@ public class DefaultPluginRepositoryTest {
     }
 
     private void assertPathExists(List<Path> paths, Path path) {
-        assertTrue("The directory must contain the file " + path, paths.contains(path));
-    }
-
-    private void assertPathDoesNotExists(List<Path> paths, Path path) {
-        assertFalse("The directory must not contain the file " + path, paths.contains(path));
+        assertTrue(paths.contains(path), "The directory must contain the file " + path);
     }
 
 }

pf4j/src/test/java/org/pf4j/DefaultPluginStatusProviderTest.java

@@ -15,20 +15,17 @@
  */
 package org.pf4j;
 
-import org.junit.Before;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.pf4j.util.FileUtils;
 
-import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Mario Franco
@@ -36,15 +33,8 @@ import static org.junit.Assert.assertTrue;
  */
 public class DefaultPluginStatusProviderTest {
 
-    private Path pluginsPath;
-
-    @Rule
-    public TemporaryFolder pluginsFolder = new TemporaryFolder();
-
-    @Before
-    public void setUp() {
-        pluginsPath = pluginsFolder.getRoot().toPath();
-    }
+    @TempDir
+    Path pluginsPath;
 
     @Test
     public void testIsPluginDisabled() throws IOException {
@@ -70,58 +60,59 @@ public class DefaultPluginStatusProviderTest {
     }
 
     @Test
-    public void testDisablePlugin() throws IOException {
+    public void testDisablePlugin() throws Exception {
         createEnabledFile();
         createDisabledFile();
 
         PluginStatusProvider statusProvider = new DefaultPluginStatusProvider(pluginsPath);
+        statusProvider.disablePlugin("plugin-1");
 
-        assertTrue(statusProvider.disablePlugin("plugin-1"));
         assertTrue(statusProvider.isPluginDisabled("plugin-1"));
         assertTrue(statusProvider.isPluginDisabled("plugin-2"));
         assertTrue(statusProvider.isPluginDisabled("plugin-3"));
     }
 
     @Test
-    public void testDisablePluginWithEnableEmpty() throws IOException {
+    public void testDisablePluginWithEnableEmpty() throws Exception {
         createDisabledFile();
 
         PluginStatusProvider statusProvider = new DefaultPluginStatusProvider(pluginsPath);
+        statusProvider.disablePlugin("plugin-1");
 
-        assertTrue(statusProvider.disablePlugin("plugin-1"));
         assertTrue(statusProvider.isPluginDisabled("plugin-1"));
         assertTrue(statusProvider.isPluginDisabled("plugin-2"));
         assertFalse(statusProvider.isPluginDisabled("plugin-3"));
     }
 
     @Test
-    public void testEnablePlugin() throws IOException {
+    public void testEnablePlugin() throws Exception {
         createEnabledFile();
 
         PluginStatusProvider statusProvider = new DefaultPluginStatusProvider(pluginsPath);
+        statusProvider.enablePlugin("plugin-2");
 
-        assertTrue(statusProvider.enablePlugin("plugin-2"));
         assertFalse(statusProvider.isPluginDisabled("plugin-1"));
         assertFalse(statusProvider.isPluginDisabled("plugin-2"));
         assertTrue(statusProvider.isPluginDisabled("plugin-3"));
     }
 
     @Test
-    public void testEnablePluginWithEnableEmpty() {
+    public void testEnablePluginWithEnableEmpty() throws Exception{
         PluginStatusProvider statusProvider = new DefaultPluginStatusProvider(pluginsPath);
+        statusProvider.enablePlugin("plugin-2");
 
-        assertTrue(statusProvider.enablePlugin("plugin-2"));
         assertFalse(statusProvider.isPluginDisabled("plugin-1"));
         assertFalse(statusProvider.isPluginDisabled("plugin-2"));
         assertFalse(statusProvider.isPluginDisabled("plugin-3"));
     }
 
     @Test
-    public void testDisablePluginWithoutDisabledFile() {
+    public void testDisablePluginWithoutDisabledFile() throws Exception {
         PluginStatusProvider statusProvider = new DefaultPluginStatusProvider(pluginsPath);
 
         assertFalse(statusProvider.isPluginDisabled("plugin-1"));
-        assertTrue(statusProvider.disablePlugin("plugin-1"));
+
+        statusProvider.disablePlugin("plugin-1");
         assertTrue(statusProvider.isPluginDisabled("plugin-1"));
     }
 
@@ -129,8 +120,8 @@ public class DefaultPluginStatusProviderTest {
         List<String> disabledPlugins = new ArrayList<>();
         disabledPlugins.add("plugin-2");
 
-        File disabledFile = pluginsFolder.newFile("disabled.txt");
-        FileUtils.writeLines(disabledPlugins, disabledFile);
+        Path disabledPath = pluginsPath.resolve("disabled.txt");
+        FileUtils.writeLines(disabledPlugins, disabledPath.toFile());
     }
 
     private void createEnabledFile() throws IOException {
@@ -138,8 +129,8 @@ public class DefaultPluginStatusProviderTest {
         enabledPlugins.add("plugin-1");
         enabledPlugins.add("plugin-2");
 
-        File enabledFile = pluginsFolder.newFile("enabled.txt");
-        FileUtils.writeLines(enabledPlugins, enabledFile);
+        Path enabledPath = pluginsPath.resolve("enabled.txt");
+        FileUtils.writeLines(enabledPlugins, enabledPath.toFile());
     }
 
 }

pf4j/src/test/java/org/pf4j/DefaultVersionManagerTest.java

@@ -16,10 +16,12 @@
 package org.pf4j;
 
 import com.github.zafarkhaja.semver.ParseException;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Decebal Suiu
@@ -28,7 +30,7 @@ public class DefaultVersionManagerTest {
 
     private VersionManager versionManager;
 
-    @Before
+    @BeforeEach
     public void init() {
         versionManager = new DefaultVersionManager();
     }
@@ -39,14 +41,14 @@ public class DefaultVersionManagerTest {
         assertTrue(versionManager.checkVersionConstraint("1.4.3", ">=1.4.0 & <1.6.0")); // range
     }
 
-    @Test(expected = IllegalArgumentException.class)
+    @Test
     public void nullOrEmptyVersion() {
-        assertFalse(versionManager.checkVersionConstraint(null, ">2.0.0"));
+        assertThrows(IllegalArgumentException.class, () -> versionManager.checkVersionConstraint(null, ">2.0.0"));
     }
 
-    @Test(expected = ParseException.class)
+    @Test
     public void invalidVersion() {
-        assertFalse(versionManager.checkVersionConstraint("1.0", ">2.0.0"));
+        assertThrows(ParseException.class, () -> versionManager.checkVersionConstraint("1.0", ">2.0.0"));
     }
 
     @Test

pf4j/src/test/java/org/pf4j/DependencyResolverTest.java

@@ -15,14 +15,16 @@
  */
 package org.pf4j;
 
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Decebal Suiu
@@ -31,7 +33,7 @@ public class DependencyResolverTest {
 
     private DependencyResolver resolver;
 
-    @Before
+    @BeforeEach
     public void init() {
         VersionManager versionManager = new DefaultVersionManager();
         resolver = new DependencyResolver(versionManager);

pf4j/src/test/java/org/pf4j/DevelopmentPluginRepositoryTest.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+/**
+ * @author Decebal Suiu
+ */
+public class DevelopmentPluginRepositoryTest {
+
+    @TempDir
+    Path pluginsPath;
+
+    @BeforeEach
+    public void setUp() throws IOException {
+        // standard maven/gradle bin folder - these should be skipped in development mode because the cause errors
+        Files.createDirectory(pluginsPath.resolve(DevelopmentPluginRepository.MAVEN_BUILD_DIR));
+        Files.createDirectory(pluginsPath.resolve(DevelopmentPluginRepository.GRADLE_BUILD_DIR));
+    }
+
+    @Test
+    public void testGetPluginArchivesInDevelopmentMode() {
+        PluginRepository repository = new DevelopmentPluginRepository(pluginsPath);
+
+        List<Path> pluginPaths = repository.getPluginPaths();
+
+        // target and build should be ignored
+        assertEquals(0, pluginPaths.size());
+        assertPathDoesNotExists(pluginPaths, pluginsPath.resolve(DevelopmentPluginRepository.MAVEN_BUILD_DIR));
+        assertPathDoesNotExists(pluginPaths, pluginsPath.resolve(DevelopmentPluginRepository.GRADLE_BUILD_DIR));
+    }
+
+    private void assertPathDoesNotExists(List<Path> paths, Path path) {
+        assertFalse(paths.contains(path), "The directory must not contain the file " + path);
+    }
+
+}

pf4j/src/test/java/org/pf4j/ExtensionAnnotationProcessorTest.java

@@ -15,13 +15,13 @@
  */
 package org.pf4j;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.pf4j.processor.ExtensionAnnotationProcessor;
 
 import java.util.Set;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Mario Franco

pf4j/src/test/java/org/pf4j/JarPluginManagerTest.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.pf4j.plugin.PluginJar;
+import org.pf4j.plugin.TestExtension;
+import org.pf4j.plugin.TestExtensionPoint;
+import org.pf4j.plugin.TestPlugin;
+
+import java.io.IOException;
+import java.nio.file.Path;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class JarPluginManagerTest {
+
+    private PluginJar pluginJar;
+    private JarPluginManager pluginManager;
+
+    @TempDir
+    Path pluginsPath;
+
+    @BeforeEach
+    public void setUp() throws IOException {
+        pluginJar = new PluginJar.Builder(pluginsPath.resolve("test-plugin.jar"), "test-plugin")
+            .pluginClass(TestPlugin.class.getName())
+            .pluginVersion("1.2.3")
+            .extension(TestExtension.class.getName())
+            .build();
+
+        pluginManager = new JarPluginManager(pluginsPath);
+    }
+
+    @AfterEach
+    public void tearDown() {
+        pluginJar = null;
+        pluginManager = null;
+    }
+
+    @Test
+    public void getExtensions() {
+        pluginManager.loadPlugins();
+        pluginManager.startPlugins();
+
+        List<TestExtensionPoint> extensions = pluginManager.getExtensions(TestExtensionPoint.class);
+        assertEquals(1, extensions.size());
+
+        String something = extensions.get(0).saySomething();
+        assertEquals(new TestExtension().saySomething(), something);
+    }
+
+    @Test
+    public void unloadPlugin() throws Exception {
+        pluginManager.loadPlugins();
+
+        assertEquals(1, pluginManager.getPlugins().size());
+
+        boolean unloaded = pluginManager.unloadPlugin(pluginJar.pluginId());
+        assertTrue(unloaded);
+
+        assertTrue(pluginJar.file().exists());
+    }
+
+    @Test
+    public void deletePlugin() throws Exception {
+        pluginManager.loadPlugins();
+
+        assertEquals(1, pluginManager.getPlugins().size());
+
+        boolean deleted = pluginManager.deletePlugin(pluginJar.pluginId());
+        assertTrue(deleted);
+
+        assertFalse(pluginJar.file().exists());
+    }
+
+}

pf4j/src/test/java/org/pf4j/JarPluginRepositoryTest.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+/**
+ * @author Decebal Suiu
+ */
+public class JarPluginRepositoryTest {
+
+    @TempDir
+    Path pluginsPath;
+
+    /**
+     * Test of {@link JarPluginRepository#deletePluginPath(Path)} method.
+     */
+    @Test
+    public void testDeletePluginPath() throws Exception {
+        PluginRepository repository = new JarPluginRepository(pluginsPath);
+
+        Path plugin1Path = Files.createDirectory(pluginsPath.resolve("plugin-1"));
+        Path plugin1JarPath = Files.createFile(pluginsPath.resolve("plugin-1.jar"));
+
+        assertFalse(repository.deletePluginPath(plugin1Path));
+
+        List<Path> pluginPaths = repository.getPluginPaths();
+        assertEquals(1, pluginPaths.size());
+
+        assertTrue(repository.deletePluginPath(plugin1JarPath));
+
+        pluginPaths = repository.getPluginPaths();
+        assertEquals(0, pluginPaths.size());
+    }
+
+}

pf4j/src/test/java/org/pf4j/LegacyExtensionFinderTest.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledOnOs;
+import org.junit.jupiter.api.io.TempDir;
+import org.pf4j.plugin.PluginJar;
+import org.pf4j.plugin.TestExtension;
+import org.pf4j.plugin.TestPlugin;
+
+import java.nio.file.Path;
+import java.util.Map;
+import java.util.Set;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.contains;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.condition.OS.WINDOWS;
+
+public class LegacyExtensionFinderTest {
+
+    @TempDir
+    Path pluginsPath;
+
+    @Test
+    @EnabledOnOs(WINDOWS)
+    public void shouldUnlockFileAfterReadingExtensionsFromPlugin() throws Exception {
+        PluginJar pluginJar = new PluginJar.Builder(pluginsPath.resolve("test-plugin.jar"), "test-plugin")
+                .pluginClass(TestPlugin.class.getName())
+                .pluginVersion("1.2.3")
+                .extension(TestExtension.class.getName())
+                .build();
+
+        assertTrue(pluginJar.file().exists());
+
+        PluginManager pluginManager = new JarPluginManager(pluginsPath);
+        pluginManager.loadPlugins();
+
+        assertEquals(1, pluginManager.getPlugins().size());
+
+        LegacyExtensionFinder extensionFinder = new LegacyExtensionFinder(pluginManager);
+        Map<String, Set<String>> pluginsStorages = extensionFinder.readPluginsStorages();
+        assertNotNull(pluginsStorages);
+
+        pluginManager.unloadPlugin(pluginJar.pluginId());
+        boolean fileDeleted = pluginJar.file().delete();
+
+        Set<String> pluginStorages = pluginsStorages.get(pluginJar.pluginId());
+        assertNotNull(pluginStorages);
+        assertEquals(1, pluginStorages.size());
+        assertThat(pluginStorages, contains(TestExtension.class.getName()));
+        assertTrue(fileDeleted);
+        assertFalse(pluginJar.file().exists());
+    }
+
+}

pf4j/src/test/java/org/pf4j/LegacyExtensionStorageTest.java

@@ -15,7 +15,7 @@
  */
 package org.pf4j;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.pf4j.processor.LegacyExtensionStorage;
 
 import java.io.IOException;
@@ -24,7 +24,7 @@ import java.io.StringReader;
 import java.util.HashSet;
 import java.util.Set;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 /**
  * @author Decebal Suiu

pf4j/src/test/java/org/pf4j/LoadPluginsTest.java

@@ -15,42 +15,42 @@
  */
 package org.pf4j;
 
-import static org.hamcrest.CoreMatchers.containsString;
-import static org.hamcrest.CoreMatchers.equalTo;
-import static org.hamcrest.CoreMatchers.startsWith;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertThat;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
-
-import java.io.File;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.pf4j.plugin.PluginZip;
+
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
-import org.junit.Before;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
-import org.pf4j.plugin.PluginZip;
+
+import static org.hamcrest.CoreMatchers.containsString;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.CoreMatchers.startsWith;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
 
 public class LoadPluginsTest {
 
     private DefaultPluginManager pluginManager;
 
-    @Rule
-    public TemporaryFolder pluginsFolder = new TemporaryFolder();
+    @TempDir
+    Path pluginsPath;
 
-    @Before
+    @BeforeEach
     public void setUp() {
-        pluginManager = new DefaultPluginManager(pluginsFolder.getRoot().toPath());
+        pluginManager = new DefaultPluginManager(pluginsPath);
     }
 
     @Test
     public void load() throws Exception {
-        PluginZip pluginZip = new PluginZip.Builder(pluginsFolder.newFile("my-plugin-1.2.3.zip"), "myPlugin")
+        PluginZip pluginZip = new PluginZip.Builder(pluginsPath.resolve("my-plugin-1.2.3.zip"), "myPlugin")
             .pluginVersion("1.2.3")
             .build();
 
@@ -64,31 +64,32 @@ public class LoadPluginsTest {
         assertEquals(pluginZip.pluginId(), pluginManager.idForPath(pluginZip.unzippedPath()));
     }
 
-    @Test(expected = IllegalArgumentException.class)
+    @Test
     public void loadNonExisting() {
-        pluginManager.loadPlugin(Paths.get("nonexisting"));
+        assertThrows(IllegalArgumentException.class, () -> pluginManager.loadPlugin(Paths.get("nonexisting")));
     }
 
-    @Test(expected = PluginAlreadyLoadedException.class)
+    @Test
     public void loadTwiceFails() throws Exception {
-        PluginZip pluginZip = new PluginZip.Builder(pluginsFolder.newFile("my-plugin-1.2.3.zip"), "myPlugin")
+        PluginZip pluginZip = new PluginZip.Builder(pluginsPath.resolve("my-plugin-1.2.3.zip"), "myPlugin")
             .pluginVersion("1.2.3")
             .build();
 
         assertNotNull(pluginManager.loadPluginFromPath(pluginZip.path()));
-        assertNull(pluginManager.loadPluginFromPath(pluginZip.path()));
+
+        assertThrows(PluginAlreadyLoadedException.class, () -> pluginManager.loadPluginFromPath(pluginZip.path()));
     }
 
     @Test
     public void loadPluginWithSameIdDifferentPathFails() throws Exception {
         String pluginId = "myPlugin";
         String pluginVersion = "1.2.3";
-        File plugin1Path = pluginsFolder.newFile("my-plugin-1.2.3.zip");
+        Path plugin1Path = pluginsPath.resolve("my-plugin-1.2.3.zip");
         PluginZip plugin1 = new PluginZip.Builder(plugin1Path, pluginId)
             .pluginVersion(pluginVersion)
             .build();
 
-        File plugin2Path = pluginsFolder.newFile("my-plugin-1.2.3-renamed.zip");
+        Path plugin2Path = pluginsPath.resolve("my-plugin-1.2.3-renamed.zip");
         PluginZip plugin2 = new PluginZip.Builder(plugin2Path, pluginId)
             .pluginVersion(pluginVersion)
             .build();
@@ -101,7 +102,7 @@ public class LoadPluginsTest {
             // Verify the second plugin is not loaded as it has the same metadata
             pluginManager.loadPluginFromPath(plugin2.path());
             fail("Expected loadPluginFromPath to fail");
-        } catch (PluginException e) {
+        } catch (PluginRuntimeException e) {
             // Check the path of the loaded plugin remains the same
             PluginWrapper loadedPlugin = pluginManager.getPlugin(pluginId);
             assertThat(loadedPlugin.getPluginPath(), equalTo(loadedPlugin1Path));
@@ -122,13 +123,13 @@ public class LoadPluginsTest {
     public void loadPluginWithSameIdDifferentVersionsFails() throws Exception {
         String pluginId = "myPlugin";
         String plugin1Version = "1.2.3";
-        File plugin1Path = pluginsFolder.newFile("my-plugin-1.2.3.zip");
+        Path plugin1Path = pluginsPath.resolve("my-plugin-1.2.3.zip");
         PluginZip plugin1 = new PluginZip.Builder(plugin1Path, pluginId)
             .pluginVersion(plugin1Version)
             .build();
 
         String plugin2Version = "2.0.0";
-        File plugin2Path = pluginsFolder.newFile("my-plugin-2.0.0.zip");
+        Path plugin2Path = pluginsPath.resolve("my-plugin-2.0.0.zip");
         PluginZip plugin2 = new PluginZip.Builder(plugin2Path, pluginId)
             .pluginVersion(plugin2Version)
             .build();
@@ -140,7 +141,7 @@ public class LoadPluginsTest {
             // Verify the second plugin is not loaded as it has the same pluginId
             pluginManager.loadPluginFromPath(plugin2.path());
             fail("Expected loadPluginFromPath to fail");
-        } catch (PluginException e) {
+        } catch (PluginRuntimeException e) {
             // Check the path and version of the loaded plugin remain the same
             PluginWrapper loadedPlugin = pluginManager.getPlugin(pluginId);
             assertThat(loadedPlugin.getPluginPath(), equalTo(loadedPlugin1Path));
@@ -150,7 +151,7 @@ public class LoadPluginsTest {
 
     @Test
     public void loadUnloadLoad() throws Exception {
-        PluginZip pluginZip = new PluginZip.Builder(pluginsFolder.newFile("my-plugin-1.2.3.zip"), "myPlugin")
+        PluginZip pluginZip = new PluginZip.Builder(pluginsPath.resolve("my-plugin-1.2.3.zip"), "myPlugin")
             .pluginVersion("1.2.3")
             .build();
 
@@ -169,7 +170,7 @@ public class LoadPluginsTest {
     public void upgrade() throws Exception {
         String pluginId = "myPlugin";
 
-        new PluginZip.Builder(pluginsFolder.newFile("my-plugin-1.2.3.zip"), pluginId)
+        new PluginZip.Builder(pluginsPath.resolve("my-plugin-1.2.3.zip"), pluginId)
             .pluginVersion("1.2.3")
             .build();
 
@@ -179,7 +180,7 @@ public class LoadPluginsTest {
         assertEquals(1, pluginManager.getPlugins().size());
         assertEquals(1, pluginManager.getStartedPlugins().size());
 
-        PluginZip pluginZip2 = new PluginZip.Builder(pluginsFolder.newFile("my-plugin-2.0.0.ZIP"), pluginId)
+        PluginZip pluginZip2 = new PluginZip.Builder(pluginsPath.resolve("my-plugin-2.0.0.ZIP"), pluginId)
             .pluginVersion("2.0.0")
             .build();
 
@@ -196,12 +197,12 @@ public class LoadPluginsTest {
 
     @Test
     public void getRoot() {
-        assertEquals(pluginsFolder.getRoot().toPath(), pluginManager.getPluginsRoot());
+        assertEquals(pluginsPath, pluginManager.getPluginsRoot());
     }
 
     @Test
-    public void notAPlugin() throws Exception {
-        pluginsFolder.newFile("not-a-zip");
+    public void notAPlugin() {
+        pluginsPath.resolve("not-a-zip");
 
         pluginManager.loadPlugins();
 
@@ -210,11 +211,11 @@ public class LoadPluginsTest {
 
     @Test
     public void deletePlugin() throws Exception {
-        PluginZip pluginZip1 = new PluginZip.Builder(pluginsFolder.newFile("my-plugin-1.2.3.zip"), "myPlugin")
+        PluginZip pluginZip1 = new PluginZip.Builder(pluginsPath.resolve("my-plugin-1.2.3.zip"), "myPlugin")
             .pluginVersion("1.2.3")
             .build();
 
-        PluginZip pluginZip3 = new PluginZip.Builder(pluginsFolder.newFile("other-3.0.0.Zip"), "other")
+        PluginZip pluginZip3 = new PluginZip.Builder(pluginsPath.resolve("other-3.0.0.Zip"), "other")
             .pluginVersion("3.0.0")
             .build();
 

pf4j/src/test/java/org/pf4j/ManifestPluginDescriptorFinderTest.java

@@ -15,19 +15,23 @@
  */
 package org.pf4j;
 
-import org.junit.Before;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.pf4j.plugin.PluginJar;
 
+import java.io.FileOutputStream;
 import java.io.IOException;
-import java.nio.charset.Charset;
+import java.io.OutputStream;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Arrays;
-import java.util.List;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.jar.Manifest;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Mario Franco
@@ -36,42 +40,32 @@ import static org.junit.Assert.*;
 public class ManifestPluginDescriptorFinderTest {
 
     private VersionManager versionManager;
-    private Path pluginsPath;
 
-    @Rule
-    public TemporaryFolder pluginsFolder = new TemporaryFolder();
+    @TempDir
+    Path pluginsPath;
 
-    @Before
+    @BeforeEach
     public void setUp() throws IOException {
-        pluginsPath = pluginsFolder.getRoot().toPath();
+        Path pluginPath = Files.createDirectories(pluginsPath.resolve("test-plugin-1"));
+        storeManifestToPath(getPlugin1Manifest(), pluginPath);
 
-        Charset charset = Charset.forName("UTF-8");
-
-        Path pluginPath = pluginsFolder.newFolder("test-plugin-1", "classes", "META-INF").toPath();
-        Files.write(pluginPath.resolve("extensions.idx"), "org.pf4j.demo.hello.HelloPlugin$HelloGreeting".getBytes());
-        Files.write(pluginPath.resolve("MANIFEST.MF"), getPlugin1Manifest(), charset);
-
-        pluginPath = pluginsFolder.newFolder("test-plugin-2", "classes", "META-INF").toPath();
-        Files.write(pluginPath.resolve("extensions.idx"), "org.pf4j.demo.hello.HelloPlugin$HelloGreeting".getBytes());
-        Files.write(pluginPath.resolve("MANIFEST.MF"), getPlugin2Manifest(), charset);
+        pluginPath = Files.createDirectories(pluginsPath.resolve("test-plugin-2"));
+        storeManifestToPath(getPlugin2Manifest(), pluginPath);
 
         // empty plugin
-        pluginsFolder.newFolder("test-plugin-3");
+        Files.createDirectories(pluginsPath.resolve("test-plugin-3"));
 
         // no plugin class
-        pluginPath = pluginsFolder.newFolder("test-plugin-4", "classes", "META-INF").toPath();
-        Files.write(pluginPath.resolve("extensions.idx"), "org.pf4j.demo.hello.HelloPlugin$HelloGreeting".getBytes());
-        Files.write(pluginPath.resolve("MANIFEST.MF"), getPlugin4Manifest(), charset);
+        pluginPath = Files.createDirectories(pluginsPath.resolve("test-plugin-4"));
+        storeManifestToPath(getPlugin4Manifest(), pluginPath);
 
         // no plugin version
-        pluginPath = pluginsFolder.newFolder("test-plugin-5", "classes", "META-INF").toPath();
-        Files.write(pluginPath.resolve("extensions.idx"), "org.pf4j.demo.hello.HelloPlugin$HelloGreeting".getBytes());
-        Files.write(pluginPath.resolve("MANIFEST.MF"), getPlugin5Manifest(), charset);
+        pluginPath = Files.createDirectories(pluginsPath.resolve("test-plugin-5"));
+        storeManifestToPath(getPlugin5Manifest(), pluginPath);
 
         // no plugin id
-        pluginPath = pluginsFolder.newFolder("test-plugin-6", "classes", "META-INF").toPath();
-        Files.write(pluginPath.resolve("extensions.idx"), "org.pf4j.demo.hello.HelloPlugin$HelloGreeting".getBytes());
-        Files.write(pluginPath.resolve("MANIFEST.MF"), getPlugin6Manifest(), charset);
+        pluginPath = Files.createDirectories(pluginsPath.resolve("test-plugin-6"));
+        storeManifestToPath(getPlugin6Manifest(), pluginPath);
 
         versionManager = new DefaultVersionManager();
     }
@@ -110,126 +104,68 @@ public class ManifestPluginDescriptorFinderTest {
     /**
      * Test of {@link ManifestPluginDescriptorFinder#find(Path)} method.
      */
-    @Test(expected = PluginException.class)
-    public void testFindNotFound() throws Exception {
+    @Test
+    public void testFindNotFound() {
         PluginDescriptorFinder descriptorFinder = new ManifestPluginDescriptorFinder();
-        descriptorFinder.find(pluginsPath.resolve("test-plugin-3"));
+        assertThrows(PluginRuntimeException.class, () -> descriptorFinder.find(pluginsPath.resolve("test-plugin-3")));
     }
 
-    private List<String> getPlugin1Manifest() {
-        String[] lines = new String[] {
-            "Manifest-Version: 1.0\n"
-            + "Implementation-Title: Test Plugin #1\n"
-            + "Implementation-Version: 0.10.0-SNAPSHOT\n"
-            + "Archiver-Version: Plexus Archiver\n"
-            + "Built-By: Mario Franco\n"
-            + "Specification-Title: Test Plugin #1\n"
-            + "Implementation-Vendor-Id: org.pf4j.demo\n"
-            + "Plugin-Version: 0.0.1\n"
-            + "Plugin-Id: test-plugin-1\n"
-            + "Plugin-Description: Test Plugin 1\n"
-            + "Plugin-Provider: Decebal Suiu\n"
-            + "Plugin-Class: org.pf4j.plugin.TestPlugin\n"
-            + "Plugin-Dependencies: test-plugin-2,test-plugin-3@~1.0\n"
-            + "Plugin-Requires: *\n"
-            + "Plugin-License: Apache-2.0\n"
-            + "Created-By: Apache Maven 3.0.5\n"
-            + "Build-Jdk: 1.8.0_45\n"
-            + "Specification-Version: 0.10.0-SNAPSHOT\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private Manifest getPlugin1Manifest() {
+        Map<String, String> map = new LinkedHashMap<>(8);
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_ID, "test-plugin-1");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_CLASS, "org.pf4j.plugin.TestPlugin");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_VERSION, "0.0.1");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_DESCRIPTION, "Test Plugin 1");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_DEPENDENCIES, "test-plugin-2,test-plugin-3@~1.0");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_REQUIRES, "*");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_LICENSE, "Apache-2.0");
+
+        return PluginJar.createManifest(map);
     }
 
-    private List<String> getPlugin2Manifest() {
-        String[] lines = new String[] {
-            "Manifest-Version: 1.0\n"
-            + "Plugin-Dependencies: \n"
-            + "Implementation-Title: Test Plugin #2\n"
-            + "Implementation-Version: 0.10.0-SNAPSHOT\n"
-            + "Archiver-Version: Plexus Archiver\n"
-            + "Built-By: Mario Franco\n"
-            + "Specification-Title: Test Plugin #2\n"
-            + "Implementation-Vendor-Id: org.pf4j.demo\n"
-            + "Plugin-Version: 0.0.1\n"
-            + "Plugin-Id: test-plugin-2\n"
-            + "Plugin-Provider: Decebal Suiu\n"
-            + "Plugin-Class: org.pf4j.plugin.TestPlugin\n"
-            + "Created-By: Apache Maven 3.0.5\n"
-            + "Build-Jdk: 1.8.0_45\n"
-            + "Specification-Version: 0.10.0-SNAPSHOT\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private Manifest getPlugin2Manifest() {
+        Map<String, String> map = new LinkedHashMap<>(5);
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_ID, "test-plugin-2");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_CLASS, "org.pf4j.plugin.TestPlugin");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_VERSION, "0.0.1");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_DEPENDENCIES, "");
+
+        return PluginJar.createManifest(map);
     }
 
-    private List<String> getPlugin4Manifest() {
-        String[] lines = new String[] {
-            "Manifest-Version: 1.0\n"
-            + "Implementation-Title: Test Plugin #4\n"
-            + "Implementation-Version: 0.10.0-SNAPSHOT\n"
-            + "Archiver-Version: Plexus Archiver\n"
-            + "Built-By: Mario Franco\n"
-            + "Specification-Title: Test Plugin #4\n"
-            + "Implementation-Vendor-Id: org.pf4j.demo\n"
-            + "Plugin-Version: 0.0.1\n"
-            + "Plugin-Id: test-plugin-2\n"
-            + "Plugin-Provider: Decebal Suiu\n"
-            + "Created-By: Apache Maven 3.0.5\n"
-            + "Build-Jdk: 1.8.0_45\n"
-            + "Specification-Version: 0.10.0-SNAPSHOT\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private Manifest getPlugin4Manifest() {
+        Map<String, String> map = new LinkedHashMap<>(3);
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_ID, "test-plugin-1");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_VERSION, "0.0.1");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+
+        return PluginJar.createManifest(map);
     }
 
-    private List<String> getPlugin5Manifest() {
-        String[] lines = new String[] {
-            "Manifest-Version: 1.0\n"
-            + "Implementation-Title: Test Plugin #5\n"
-            + "Implementation-Version: 0.10.0-SNAPSHOT\n"
-            + "Archiver-Version: Plexus Archiver\n"
-            + "Built-By: Mario Franco\n"
-            + "Specification-Title: Test Plugin #5\n"
-            + "Implementation-Vendor-Id: org.pf4j.demo\n"
-            + "Plugin-Id: test-plugin-2\n"
-            + "Plugin-Provider: Decebal Suiu\n"
-            + "Plugin-Class: org.pf4j.plugin.TestPlugin\n"
-            + "Created-By: Apache Maven 3.0.5\n"
-            + "Build-Jdk: 1.8.0_45\n"
-            + "Specification-Version: 0.10.0-SNAPSHOT\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private Manifest getPlugin5Manifest() {
+        Map<String, String> map = new LinkedHashMap<>(3);
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_ID, "test-plugin-2");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_CLASS, "org.pf4j.plugin.TestPlugin");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+
+        return PluginJar.createManifest(map);
+    }
+
+    private Manifest getPlugin6Manifest() {
+        Map<String, String> map = new LinkedHashMap<>(2);
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_CLASS, "org.pf4j.plugin.TestPlugin");
+        map.put(ManifestPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+
+        return PluginJar.createManifest(map);
     }
 
-    private List<String> getPlugin6Manifest() {
-        String[] lines = new String[] {
-            "Manifest-Version: 1.0\n"
-            + "Implementation-Title: Test Plugin #6\n"
-            + "Implementation-Version: 0.10.0-SNAPSHOT\n"
-            + "Archiver-Version: Plexus Archiver\n"
-            + "Built-By: Mario Franco\n"
-            + "Specification-Title: Test Plugin #6\n"
-            + "Implementation-Vendor-Id: org.pf4j.demo\n"
-            + "Plugin-Provider: Decebal Suiu\n"
-            + "Plugin-Class: org.pf4j.plugin.TestPlugin\n"
-            + "Created-By: Apache Maven 3.0.5\n"
-            + "Build-Jdk: 1.8.0_45\n"
-            + "Specification-Version: 0.10.0-SNAPSHOT\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private void storeManifestToPath(Manifest manifest, Path pluginPath) throws IOException {
+        Path path = Files.createDirectory(pluginPath.resolve("META-INF"));
+        try (OutputStream output = new FileOutputStream(path.resolve("MANIFEST.MF").toFile())) {
+            manifest.write(output);
+        }
     }
 
 }

pf4j/src/test/java/org/pf4j/PluginDependencyTest.java

@@ -15,9 +15,12 @@
  */
 package org.pf4j;
 
-import org.junit.Test;
 
-import static org.junit.Assert.*;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 /**
  * @author Mario Franco
@@ -32,33 +35,33 @@ public class PluginDependencyTest {
         PluginDependency instance = new PluginDependency("test");
         assertEquals("test", instance.getPluginId());
         assertEquals("*", instance.getPluginVersionSupport());
-        assertEquals(false, instance.isOptional());
+        assertFalse(instance.isOptional());
 
         instance = new PluginDependency("test@");
         assertEquals("test", instance.getPluginId());
         assertEquals("*", instance.getPluginVersionSupport());
-        assertEquals(false, instance.isOptional());
+        assertFalse(instance.isOptional());
 
         instance = new PluginDependency("test?");
         assertEquals("test", instance.getPluginId());
         assertEquals("*", instance.getPluginVersionSupport());
-        assertEquals(true, instance.isOptional());
+        assertTrue(instance.isOptional());
 
         instance = new PluginDependency("test?@");
         assertEquals("test", instance.getPluginId());
         assertEquals("*", instance.getPluginVersionSupport());
-        assertEquals(true, instance.isOptional());
+        assertTrue(instance.isOptional());
 
         instance = new PluginDependency("test@1.0");
         assertEquals("test", instance.getPluginId());
         assertEquals("1.0", instance.getPluginVersionSupport());
-        assertEquals(false, instance.isOptional());
+        assertFalse(instance.isOptional());
         assertEquals("PluginDependency [pluginId=test, pluginVersionSupport=1.0, optional=false]", instance.toString());
 
         instance = new PluginDependency("test?@1.0");
         assertEquals("test", instance.getPluginId());
         assertEquals("1.0", instance.getPluginVersionSupport());
-        assertEquals(true, instance.isOptional());
+        assertTrue(instance.isOptional());
         assertEquals("PluginDependency [pluginId=test, pluginVersionSupport=1.0, optional=true]", instance.toString());
     }
 

pf4j/src/test/java/org/pf4j/PropertiesPluginDescriptorFinderTest.java

@@ -15,55 +15,57 @@
  */
 package org.pf4j;
 
-import org.junit.Before;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.pf4j.plugin.PluginZip;
+import org.pf4j.plugin.TestPlugin;
 
+import java.io.FileOutputStream;
 import java.io.IOException;
-import java.nio.charset.Charset;
+import java.io.OutputStreamWriter;
+import java.io.Writer;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.Arrays;
-import java.util.List;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Properties;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 public class PropertiesPluginDescriptorFinderTest {
 
     private VersionManager versionManager;
-    private Path pluginsPath;
 
-    @Rule
-    public TemporaryFolder pluginsFolder = new TemporaryFolder();
+    @TempDir
+    Path pluginsPath;
 
-    @Before
+    @BeforeEach
     public void setUp() throws IOException {
-        pluginsPath = pluginsFolder.getRoot().toPath();
+        Path pluginPath = Files.createDirectory(pluginsPath.resolve("test-plugin-1"));
+        storePropertiesToPath(getPlugin1Properties(), pluginPath);
 
-        Charset charset = Charset.forName("UTF-8");
-
-        Path pluginPath = pluginsFolder.newFolder("test-plugin-1").toPath();
-        Files.write(pluginPath.resolve("plugin.properties"), getPlugin1Properties(), charset);
-
-        pluginPath = pluginsFolder.newFolder("test-plugin-2").toPath();
-        Files.write(pluginPath.resolve("plugin.properties"), getPlugin2Properties(), charset);
+        pluginPath = Files.createDirectory(pluginsPath.resolve("test-plugin-2"));
+        storePropertiesToPath(getPlugin2Properties(), pluginPath);
 
         // empty plugin
-        pluginsFolder.newFolder("test-plugin-3");
+        Files.createDirectories(pluginsPath.resolve("test-plugin-3"));
 
         // no plugin class
-        pluginPath = pluginsFolder.newFolder("test-plugin-4").toPath();
-        Files.write(pluginPath.resolve("plugin.properties"), getPlugin4Properties(), charset);
+        pluginPath = Files.createDirectory(pluginsPath.resolve("test-plugin-4"));
+        storePropertiesToPath(getPlugin4Properties(), pluginPath);
 
         // no plugin version
-        pluginPath = pluginsFolder.newFolder("test-plugin-5").toPath();
-        Files.write(pluginPath.resolve("plugin.properties"), getPlugin5Properties(), charset);
+        pluginPath = Files.createDirectory(pluginsPath.resolve("test-plugin-5"));
+        storePropertiesToPath(getPlugin5Properties(), pluginPath);
 
         // no plugin id
-        pluginPath = pluginsFolder.newFolder("test-plugin-6").toPath();
-        Files.write(pluginPath.resolve("plugin.properties"), getPlugin6Properties(), charset);
+        pluginPath = Files.createDirectory(pluginsPath.resolve("test-plugin-6"));
+        storePropertiesToPath(getPlugin6Properties(), pluginPath);
 
         versionManager = new DefaultVersionManager();
     }
@@ -77,7 +79,7 @@ public class PropertiesPluginDescriptorFinderTest {
 
         assertEquals("test-plugin-1", plugin1.getPluginId());
         assertEquals("Test Plugin 1", plugin1.getPluginDescription());
-        assertEquals("org.pf4j.plugin.TestPlugin", plugin1.getPluginClass());
+        assertEquals(TestPlugin.class.getName(), plugin1.getPluginClass());
         assertEquals("0.0.1", plugin1.getVersion());
         assertEquals("Decebal Suiu", plugin1.getProvider());
         assertEquals(2, plugin1.getDependencies().size());
@@ -91,7 +93,7 @@ public class PropertiesPluginDescriptorFinderTest {
 
         assertEquals("test-plugin-2", plugin2.getPluginId());
         assertEquals("", plugin2.getPluginDescription());
-        assertEquals("org.pf4j.plugin.TestPlugin", plugin2.getPluginClass());
+        assertEquals(TestPlugin.class.getName(), plugin2.getPluginClass());
         assertEquals("0.0.1", plugin2.getVersion());
         assertEquals("Decebal Suiu", plugin2.getProvider());
         assertEquals(0, plugin2.getDependencies().size());
@@ -99,98 +101,75 @@ public class PropertiesPluginDescriptorFinderTest {
         assertTrue(versionManager.checkVersionConstraint("1.0.0", plugin2.getRequires()));
     }
 
-    @Test(expected = PluginException.class)
-    public void testNotFound() throws Exception {
+    @Test
+    public void testNotFound() {
         PluginDescriptorFinder descriptorFinder = new PropertiesPluginDescriptorFinder();
-        descriptorFinder.find(pluginsPath.resolve("test-plugin-3"));
+        assertThrows(PluginRuntimeException.class, () -> descriptorFinder.find(pluginsPath.resolve("test-plugin-3")));
     }
 
-    @Test
-    public void findInJar() throws Exception {
-        PluginZip pluginJar = new PluginZip.Builder(pluginsFolder.newFile("my-plugin-1.2.3.jar"), "myPlugin")
-            .pluginVersion("1.2.3")
-            .build();
+    private Properties getPlugin1Properties() {
+        Map<String, String> map = new LinkedHashMap<>(8);
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_ID, "test-plugin-1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_CLASS, TestPlugin.class.getName());
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_VERSION, "0.0.1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_DESCRIPTION, "Test Plugin 1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_DEPENDENCIES, "test-plugin-2,test-plugin-3@~1.0");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_REQUIRES, ">=1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_LICENSE, "Apache-2.0");
+
+        return PluginZip.createProperties(map);
+    }
 
-        assertTrue(Files.exists(pluginJar.path()));
+    private Properties getPlugin2Properties() {
+        Map<String, String> map = new LinkedHashMap<>(5);
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_ID, "test-plugin-2");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_CLASS, TestPlugin.class.getName());
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_VERSION, "0.0.1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_DEPENDENCIES, "");
 
-        PluginDescriptorFinder descriptorFinder = new PropertiesPluginDescriptorFinder();
-        PluginDescriptor pluginDescriptor = descriptorFinder.find(pluginJar.path());
-        assertNotNull(pluginDescriptor);
-        assertEquals("myPlugin", pluginJar.pluginId());
-        assertEquals("1.2.3", pluginJar.pluginVersion());
+        return PluginZip.createProperties(map);
     }
 
-    private List<String> getPlugin1Properties() {
-        String[] lines = new String[] {
-            "plugin.id=test-plugin-1\n"
-            + "plugin.version=0.0.1\n"
-            + "plugin.description=Test Plugin 1\n"
-            + "plugin.provider=Decebal Suiu\n"
-            + "plugin.class=org.pf4j.plugin.TestPlugin\n"
-            + "plugin.dependencies=test-plugin-2,test-plugin-3@~1.0\n"
-            + "plugin.requires=>=1\n"
-            + "plugin.license=Apache-2.0\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
-    }
+    private Properties getPlugin4Properties() {
+        Map<String, String> map = new LinkedHashMap<>(5);
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_ID, "test-plugin-2");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_VERSION, "0.0.1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_DEPENDENCIES, "");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_REQUIRES, "*");
 
-    private List<String> getPlugin2Properties() {
-        String[] lines = new String[] {
-            "plugin.id=test-plugin-2\n"
-            + "plugin.version=0.0.1\n"
-            + "plugin.provider=Decebal Suiu\n"
-            + "plugin.class=org.pf4j.plugin.TestPlugin\n"
-            + "plugin.dependencies=\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+        return PluginZip.createProperties(map);
     }
 
-    private List<String> getPlugin4Properties() {
-        String[] lines = new String[] {
-            "plugin.id=test-plugin-2\n"
-            + "plugin.version=0.0.1\n"
-            + "plugin.provider=Decebal Suiu\n"
-            + "plugin.dependencies=\n"
-            + "plugin.requires=*\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private Properties getPlugin5Properties() {
+        Map<String, String> map = new LinkedHashMap<>(5);
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_ID, "test-plugin-2");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_CLASS, TestPlugin.class.getName());
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_DEPENDENCIES, "");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_REQUIRES, "*");
+
+        return PluginZip.createProperties(map);
     }
 
-    private List<String> getPlugin5Properties() {
-        String[] lines = new String[] {
-            "plugin.id=test-plugin-2\n"
-            + "plugin.provider=Decebal Suiu\n"
-            + "plugin.class=org.pf4j.plugin.TestPlugin\n"
-            + "plugin.dependencies=\n"
-            + "plugin.requires=*\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private Properties getPlugin6Properties() {
+        Map<String, String> map = new LinkedHashMap<>(5);
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_CLASS, TestPlugin.class.getName());
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_VERSION, "0.0.1");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_PROVIDER, "Decebal Suiu");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_DEPENDENCIES, "");
+        map.put(PropertiesPluginDescriptorFinder.PLUGIN_REQUIRES, "*");
+
+        return PluginZip.createProperties(map);
     }
 
-    private List<String> getPlugin6Properties() {
-        String[] lines = new String[] {
-            "plugin.version=0.0.1\n"
-            + "plugin.provider=Decebal Suiu\n"
-            + "plugin.class=org.pf4j.plugin.TestPlugin\n"
-            + "plugin.dependencies=\n"
-            + "plugin.requires=*\n"
-            + "\n"
-            + ""
-        };
-
-        return Arrays.asList(lines);
+    private void storePropertiesToPath(Properties properties, Path pluginPath) throws IOException {
+        Path path = pluginPath.resolve(PropertiesPluginDescriptorFinder.DEFAULT_PROPERTIES_FILE_NAME);
+        try (Writer writer = new OutputStreamWriter(new FileOutputStream(path.toFile()), StandardCharsets.UTF_8)) {
+            properties.store(writer, "");
+        }
     }
 
 }

pf4j/src/test/java/org/pf4j/SingletonExtensionFactoryTest.java

@@ -15,11 +15,12 @@
  */
 package org.pf4j;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.pf4j.plugin.FailTestExtension;
 import org.pf4j.plugin.TestExtension;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertSame;
 
 /**
  * @author Decebal Suiu

pf4j/src/test/java/org/pf4j/plugin/ClassDataProvider.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j.plugin;
+
+/**
+ * Defines the interface for classes that know to supply class data for a class name.
+ * The idea is to have the possibility to retrieve the data for a class from different sources:
+ * <ul>
+ * <li>Class path - the class is already loaded by the class loader</li>
+ * <li>String - the string (the source code) is compiled dynamically via {@link javax.tools.JavaCompiler}</>
+ * <li>Generate the source code programmatically using something like {@code https://github.com/square/javapoet}</li>
+ * </ul>
+ *
+ * @author Decebal Suiu
+ */
+public interface ClassDataProvider {
+
+    byte[] getClassData(String className);
+
+}

pf4j/src/test/java/org/pf4j/plugin/DefaultClassDataProvider.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j.plugin;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+/**
+ * Get class data from the class path.
+ *
+ * @author Decebal Suiu
+ */
+public class DefaultClassDataProvider implements ClassDataProvider {
+
+    @Override
+    public byte[] getClassData(String className) {
+        String path = className.replace('.', '/') + ".class";
+        InputStream classDataStream = getClass().getClassLoader().getResourceAsStream(path);
+        if (classDataStream == null) {
+            throw new RuntimeException("Cannot find class data");
+        }
+
+        try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
+            copyStream(classDataStream, outputStream);
+            return outputStream.toByteArray();
+        } catch (IOException e) {
+            throw new RuntimeException(e.getMessage(), e);
+        }
+    }
+
+    private void copyStream(InputStream in, OutputStream out) throws IOException {
+        byte[] buffer = new byte[1024];
+
+        int bytesRead;
+        while ((bytesRead = in.read(buffer)) != -1) {
+            out.write(buffer, 0, bytesRead);
+        }
+    }
+
+}

pf4j/src/test/java/org/pf4j/plugin/FailTestExtension.java

@@ -26,4 +26,9 @@ public class FailTestExtension implements TestExtensionPoint {
     public FailTestExtension(String name) {
     }
 
+    @Override
+    public String saySomething() {
+        return "I am a fail test extension";
+    }
+
 }

pf4j/src/test/java/org/pf4j/plugin/PluginJar.java

@@ -0,0 +1,200 @@
+/*
+ * Copyright (C) 2012-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j.plugin;
+
+import org.pf4j.ManifestPluginDescriptorFinder;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.PrintWriter;
+import java.nio.file.Path;
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.jar.Attributes;
+import java.util.jar.JarEntry;
+import java.util.jar.JarOutputStream;
+import java.util.jar.Manifest;
+
+/**
+ * Represents a plugin {@code jar} file.
+ * The {@code MANIFEST.MF} file is created on the fly from the information supplied in {@link Builder}.
+ *
+ * @author Decebal Suiu
+ */
+public class PluginJar {
+
+    private final Path path;
+    private final String pluginId;
+    private final String pluginClass;
+    private final String pluginVersion;
+
+    protected PluginJar(Builder builder) {
+        this.path = builder.path;
+        this.pluginId = builder.pluginId;
+        this.pluginClass = builder.pluginClass;
+        this.pluginVersion = builder.pluginVersion;
+    }
+
+    public Path path() {
+        return path;
+    }
+
+    public File file() {
+        return path.toFile();
+    }
+
+    public String pluginClass() {
+        return pluginClass;
+    }
+
+    public String pluginId() {
+        return pluginId;
+    }
+
+    public String pluginVersion() {
+        return pluginVersion;
+    }
+
+    public static Manifest createManifest(Map<String, String> map) {
+        Manifest manifest = new Manifest();
+        Attributes attributes = manifest.getMainAttributes();
+        attributes.put(Attributes.Name.MANIFEST_VERSION, "1.0.0");
+        for (Map.Entry<String, String> entry : map.entrySet()) {
+            attributes.put(new Attributes.Name(entry.getKey()), entry.getValue());
+        }
+
+        return manifest;
+    }
+
+    public static class Builder {
+
+        private final Path path;
+        private final String pluginId;
+
+        private String pluginClass;
+        private String pluginVersion;
+        private Map<String, String> manifestAttributes = new LinkedHashMap<>();
+        private Set<String> extensions = new LinkedHashSet<>();
+        private ClassDataProvider classDataProvider = new DefaultClassDataProvider();
+
+        public Builder(Path path, String pluginId) {
+            this.path = path;
+            this.pluginId = pluginId;
+        }
+
+        public Builder pluginClass(String pluginClass) {
+            this.pluginClass = pluginClass;
+
+            return this;
+        }
+
+        public Builder pluginVersion(String pluginVersion) {
+            this.pluginVersion = pluginVersion;
+
+            return this;
+        }
+
+        /**
+         * Add extra attributes to the {@code manifest} file.
+         * As possible attribute name please see {@link ManifestPluginDescriptorFinder}.
+         */
+        public Builder manifestAttributes(Map<String, String> manifestAttributes) {
+            this.manifestAttributes.putAll(manifestAttributes);
+
+            return this;
+        }
+
+        /**
+         * Add extra attribute to the {@code manifest} file.
+         * As possible attribute name please see {@link ManifestPluginDescriptorFinder}.
+         */
+        public Builder manifestAttribute(String name, String value) {
+            manifestAttributes.put(name, value);
+
+            return this;
+        }
+
+        public Builder extension(String extensionClassName) {
+            extensions.add(extensionClassName);
+
+            return this;
+        }
+
+        public Builder classDataProvider(ClassDataProvider classDataProvider) {
+             this.classDataProvider = classDataProvider;
+
+             return this;
+        }
+
+        public PluginJar build() throws IOException {
+            Manifest manifest = createManifest();
+            try (OutputStream outputStream = new FileOutputStream(path.toFile())) {
+                JarOutputStream jarOutputStream = new JarOutputStream(outputStream, manifest);
+                if (!extensions.isEmpty()) {
+                    // add extensions.idx
+                    JarEntry jarEntry = new JarEntry("META-INF/extensions.idx");
+                    jarOutputStream.putNextEntry(jarEntry);
+                    jarOutputStream.write(extensionsAsByteArray());
+                    jarOutputStream.closeEntry();
+                    // add extensions classes
+                    for (String extension : extensions) {
+                        String extensionPath = extension.replace('.', '/') + ".class";
+                        JarEntry classEntry = new JarEntry(extensionPath);
+                        jarOutputStream.putNextEntry(classEntry);
+                        jarOutputStream.write(classDataProvider.getClassData(extension));
+                        jarOutputStream.closeEntry();
+                    }
+                }
+                jarOutputStream.close();
+            }
+
+            return new PluginJar(this);
+        }
+
+        private Manifest createManifest() {
+            Map<String, String> map = new LinkedHashMap<>();
+            map.put(ManifestPluginDescriptorFinder.PLUGIN_ID, pluginId);
+            map.put(ManifestPluginDescriptorFinder.PLUGIN_VERSION, pluginVersion);
+            if (pluginClass != null) {
+                map.put(ManifestPluginDescriptorFinder.PLUGIN_CLASS, pluginClass);
+            }
+            if (manifestAttributes != null) {
+                map.putAll(manifestAttributes);
+            }
+
+            return PluginJar.createManifest(map);
+        }
+
+        private byte[] extensionsAsByteArray() throws IOException {
+            try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
+                PrintWriter writer = new PrintWriter(outputStream);
+                for (String extension : extensions) {
+                    writer.println(extension);
+                }
+                writer.flush();
+
+                return outputStream.toByteArray();
+            }
+        }
+
+    }
+
+}

pf4j/src/test/java/org/pf4j/plugin/PluginZip.java

@@ -15,44 +15,54 @@
  */
 package org.pf4j.plugin;
 
+import org.pf4j.PropertiesPluginDescriptorFinder;
+
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.nio.file.Path;
+import java.util.LinkedHashMap;
+import java.util.Map;
 import java.util.Properties;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipOutputStream;
 
 /**
- * Represents a plugin zip/jar file.
- * The "plugin.properties" file is created on the fly from the information supplied in Builder.
+ * Represents a plugin {@code zip} file.
+ * The {@code plugin.properties} file is created on the fly from the information supplied in {@link Builder}.
  *
  * @author Decebal Suiu
  */
 public class PluginZip {
 
-    private final File file;
+    private final Path path;
     private final String pluginId;
+    private final String pluginClass;
     private final String pluginVersion;
 
     protected PluginZip(Builder builder) {
-        this.file = builder.file;
+        this.path = builder.path;
         this.pluginId = builder.pluginId;
+        this.pluginClass = builder.pluginClass;
         this.pluginVersion = builder.pluginVersion;
     }
 
-    public File file() {
-        return file;
+    public Path path() {
+        return path;
     }
 
-    public Path path() {
-        return file.toPath();
+    public File file() {
+        return path.toFile();
     }
 
     public String pluginId() {
         return pluginId;
     }
 
+    public String pluginClass() {
+        return pluginClass;
+    }
+
     public String pluginVersion() {
         return pluginVersion;
     }
@@ -64,24 +74,59 @@ public class PluginZip {
         return path.getParent().resolve(fileName.substring(0, fileName.length() - 4)); // without ".zip" suffix
     }
 
+    public static Properties createProperties(Map<String, String> map) {
+        Properties properties = new Properties();
+        properties.putAll(map);
+
+        return properties;
+    }
+
     public static class Builder {
 
-        private final File file;
+        private final Path path;
         private final String pluginId;
 
+        private String pluginClass;
         private String pluginVersion;
+        private Map<String, String> properties = new LinkedHashMap<>();
 
-        public Builder(File file, String pluginId) {
-            this.file = file;
+        public Builder(Path path, String pluginId) {
+            this.path = path;
             this.pluginId = pluginId;
         }
 
+        public Builder pluginClass(String pluginClass) {
+            this.pluginClass = pluginClass;
+
+            return this;
+        }
+
         public Builder pluginVersion(String pluginVersion) {
             this.pluginVersion = pluginVersion;
 
             return this;
         }
 
+        /**
+         * Add extra properties to the {@code properties} file.
+         * As possible attribute name please see {@link PropertiesPluginDescriptorFinder}.
+         */
+        public Builder properties(Map<String, String> properties) {
+            this.properties.putAll(properties);
+
+            return this;
+        }
+
+        /**
+         * Add extra property to the {@code properties} file.
+         * As possible property name please see {@link PropertiesPluginDescriptorFinder}.
+         */
+        public Builder property(String name, String value) {
+            properties.put(name, value);
+
+            return this;
+        }
+
         public PluginZip build() throws IOException {
             createPropertiesFile();
 
@@ -89,15 +134,20 @@ public class PluginZip {
         }
 
         protected void createPropertiesFile() throws IOException {
-            Properties properties = new Properties();
-            properties.setProperty("plugin.id", pluginId);
-            properties.setProperty("plugin.version", pluginVersion);
-            properties.setProperty("plugin.class", "org.pf4j.plugin.TestPlugin");
-
-            ZipOutputStream outputStream = new ZipOutputStream(new FileOutputStream(file));
-            ZipEntry propertiesFile = new ZipEntry("plugin.properties");
+            Map<String, String> map = new LinkedHashMap<>();
+            map.put(PropertiesPluginDescriptorFinder.PLUGIN_ID, pluginId);
+            map.put(PropertiesPluginDescriptorFinder.PLUGIN_VERSION, pluginVersion);
+            if (pluginClass != null) {
+                map.put(PropertiesPluginDescriptorFinder.PLUGIN_CLASS, pluginClass);
+            }
+            if (properties != null) {
+                map.putAll(properties);
+            }
+
+            ZipOutputStream outputStream = new ZipOutputStream(new FileOutputStream(path.toFile()));
+            ZipEntry propertiesFile = new ZipEntry(PropertiesPluginDescriptorFinder.DEFAULT_PROPERTIES_FILE_NAME);
             outputStream.putNextEntry(propertiesFile);
-            properties.store(outputStream, "");
+            createProperties(map).store(outputStream, "");
             outputStream.closeEntry();
             outputStream.close();
         }

pf4j/src/test/java/org/pf4j/plugin/TestExtension.java

@@ -23,4 +23,9 @@ import org.pf4j.Extension;
 @Extension
 public class TestExtension implements TestExtensionPoint {
 
+    @Override
+    public String saySomething() {
+        return "I am a test extension";
+    }
+
 }

pf4j/src/test/java/org/pf4j/plugin/TestExtensionPoint.java

@@ -22,4 +22,6 @@ import org.pf4j.ExtensionPoint;
  */
 public interface TestExtensionPoint extends ExtensionPoint {
 
+    String saySomething();
+
 }

pf4j/src/test/java/org/pf4j/processor/ServiceProviderExtensionStorageTest.java

@@ -16,19 +16,23 @@
 
 package org.pf4j.processor;
 
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 import javax.annotation.processing.Filer;
 import javax.tools.FileObject;
 import javax.tools.StandardLocation;
 import java.io.IOException;
 import java.io.StringReader;
-import java.util.*;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
 
+import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.core.Is.is;
-import static org.junit.Assert.*;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.BDDMockito.given;
-import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.mock;
 
 /**
@@ -46,7 +50,6 @@ public class ServiceProviderExtensionStorageTest {
         assertThat(entries.contains("World"), is(true));
     }
 
-
     @Test
     public void ensureReadingExtensionsProducesCorrectListOfExtensions() {
         final StringReader file = new StringReader("#hello\n    World");
@@ -56,6 +59,7 @@ public class ServiceProviderExtensionStorageTest {
 
         given(processor.getExtensions()).willReturn(extensions);
         ServiceProviderExtensionStorage extensionStorage = new ServiceProviderExtensionStorage(processor) {
+
             @Override
             protected Filer getFiler() {
                 try {
@@ -72,6 +76,7 @@ public class ServiceProviderExtensionStorageTest {
                     throw new IllegalStateException("Shouldn't have gotten here");
                 }
             }
+
         };
 
         Map<String, Set<String>> read = extensionStorage.read();

pf4j/src/test/java/org/pf4j/util/DirectedGraphTest.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2015 Decebal Suiu
+ *
+ * Licensed under the Apache License, Version 2.0 (the 'License');
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an 'AS IS' BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.pf4j.util;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+/**
+ * @author Decebal Suiu
+ */
+public class DirectedGraphTest {
+
+    private static DirectedGraph<Character> graph;
+
+    @BeforeAll
+    public static void setUp() {
+        graph = new DirectedGraph<>();
+
+        // add vertex
+        graph.addVertex('A');
+        graph.addVertex('B');
+        graph.addVertex('C');
+        graph.addVertex('D');
+        graph.addVertex('E');
+        graph.addVertex('F');
+        graph.addVertex('G');
+
+        // add edges
+        graph.addEdge('A', 'B');
+        graph.addEdge('B', 'C');
+        graph.addEdge('B', 'F');
+        graph.addEdge('D', 'E');
+        graph.addEdge('F', 'G');
+    }
+
+    @Test
+    public void reverseTopologicalSort() {
+        List<Character> result = graph.reverseTopologicalSort();
+        List<Character> expected = Arrays.asList('C', 'G', 'F', 'B', 'A', 'E', 'D');
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void topologicalSort() {
+        List<Character> result = graph.topologicalSort();
+        List<Character> expected = Arrays.asList('D', 'E', 'A', 'B', 'F', 'G', 'C');
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void inDegree() {
+        Map<Character, Integer> result = graph.inDegree();
+        Map<Character, Integer> expected = new HashMap<>(7);
+        expected.put('A', 0);
+        expected.put('B', 1);
+        expected.put('C', 1);
+        expected.put('D', 0);
+        expected.put('E', 1);
+        expected.put('F', 1);
+        expected.put('G', 1);
+        assertEquals(expected, result);
+    }
+
+    @Test
+    public void outDegree() {
+        Map<Character, Integer> result = graph.outDegree();
+        Map<Character, Integer> expected = new HashMap<>(7);
+        expected.put('A', 1);
+        expected.put('B', 2);
+        expected.put('C', 0);
+        expected.put('D', 1);
+        expected.put('E', 0);
+        expected.put('F', 1);
+        expected.put('G', 0);
+        assertEquals(expected, result);
+    }
+
+}

pf4j/src/test/java/org/pf4j/util/FileUtilsTest.java

@@ -15,24 +15,24 @@
  */
 package org.pf4j.util;
 
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.pf4j.plugin.PluginZip;
 
 import java.nio.file.Files;
 import java.nio.file.Path;
 
-import static org.junit.Assert.*;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 public class FileUtilsTest {
 
-    @Rule
-    public TemporaryFolder testFolder = new TemporaryFolder();
+    @TempDir
+    Path pluginsPath;
 
     @Test
     public void expandIfZip() throws Exception {
-        PluginZip pluginZip = new PluginZip.Builder(testFolder.newFile("my-plugin-1.2.3.zip"), "myPlugin")
+        PluginZip pluginZip = new PluginZip.Builder(pluginsPath.resolve("my-plugin-1.2.3.zip"), "myPlugin")
             .pluginVersion("1.2.3")
             .build();
 
@@ -41,10 +41,10 @@ public class FileUtilsTest {
         assertTrue(Files.exists(unzipped.resolve("plugin.properties")));
 
         // File without .suffix
-        Path extra = testFolder.newFile("extra").toPath();
+        Path extra = pluginsPath.resolve("extra");
         assertEquals(extra, FileUtils.expandIfZip(extra));
         // Folder
-        Path folder = testFolder.newFile("folder").toPath();
+        Path folder = pluginsPath.resolve("folder");
         assertEquals(folder, FileUtils.expandIfZip(folder));
     }