vaadin-framework/compatibility-client/pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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>
	<parent>
		<groupId>com.vaadin</groupId>
		<artifactId>vaadin-root</artifactId>
		<version>8.0-SNAPSHOT</version>
	</parent>
	<artifactId>vaadin-compatibility-client</artifactId>
	<name>vaadin-compatibility-client</name>
	<packaging>jar</packaging>

	<url>https://vaadin.com/</url>
	<description>Vaadin 7 compatibility package for Vaadin 8</description>

	<dependencies>
		<!-- Project modules -->
		<dependency>
			<groupId>com.vaadin</groupId>
			<artifactId>vaadin-client</artifactId>
			<version>${project.version}</version>
		</dependency>
		<dependency>
			<groupId>${project.groupId}</groupId>
			<artifactId>vaadin-compatibility-server</artifactId>
			<version>${project.version}</version>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-checkstyle-plugin</artifactId>
				<executions>
					<execution>
						<goals>
							<goal>checkstyle</goal>
						</goals>
						<phase>process-sources</phase>
					</execution>
				</executions>
			</plugin>

            <plugin>
                <artifactId>maven-resources-plugin</artifactId>
                <executions>
                    <!-- Copy .java files to package -->
                    <execution>
                        <id>copy-sources</id>
                        <!-- here the phase you need -->
                        <phase>prepare-package</phase>
                        <goals>
                            <goal>copy-resources</goal>
                        </goals>
                        <configuration>
                            <outputDirectory>${project.build.outputDirectory}</outputDirectory>
                            <resources>
                                <resource>
                                    <directory>src/main/resources</directory>
                                    <filtering>false</filtering>
                                </resource>
                                <resource>
                                    <directory>src/main/java</directory>
                                    <filtering>false</filtering>
                                </resource>
                            </resources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-surefire-plugin</artifactId>
			</plugin>
		</plugins>
	</build>

</project>