Use gradle toolchain to specify the jdk version and vendor, e.g.

> gradle -no-build-cache -PjdkVersion=16 -PjdkVendor=oracle clean check

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1898288 13f79535-47bb-0310-9956-ffa450edef68

build.gradle

         saxonVersion = '11.2'
         apiGuardianVersion = '1.1.2'
 
+        jdkVersion = (project.properties['jdkVersion'] ?: '8') as int
+        // see https://github.com/gradle/gradle/blob/master/subprojects/jvm-services/src/main/java/org/gradle/internal/jvm/inspection/JvmVendor.java
+        jdkVendor = (project.properties['jdkVendor'] ?: '') as String
+
         JAVA9_SRC = 'src/main/java9'
         JAVA9_OUT = "${buildDir}/classes/java9/main/"
         TEST9_SRC = 'src/test/java9'
         options.incremental = true
 
         onlyIf {
-            (name != "compileJava9" && name != "compileTest9") || JavaVersion.current() != JavaVersion.VERSION_1_8
+            (name != "compileJava9" && name != "compileTest9") // || jdkVersion > 8
         }
     }
 
-    sourceCompatibility = JavaVersion.VERSION_1_8
-    targetCompatibility = JavaVersion.VERSION_1_8
-
     repositories {
         mavenCentral()
         maven {
     }
 
     java {
+        toolchain {
+            languageVersion.set(JavaLanguageVersion.of(jdkVersion))
+            if (jdkVendor != '') vendor.set(JvmVendorSpec.matching(jdkVendor))
+        }
         withJavadocJar()
         withSourcesJar()
     }
     javadoc {
         failOnError = true
         maxMemory = "1024M"
+        javadocTool = javaToolchains.javadocToolFor {
+            languageVersion = JavaLanguageVersion.of(11)
+        }
+
         doFirst {
             options {
-                if (JavaVersion.current().isJava9Compatible()) {
-                    addBooleanOption('html5', true)
-                }
+                addBooleanOption('html5', true)
                 addBooleanOption('Xdoclint:all,-missing', true)
                 links 'https://poi.apache.org/apidocs/dev/'
                 links 'https://docs.oracle.com/javase/8/docs/api/'
             junitXml.required = true
         }
 
+        javaLauncher = javaToolchains.launcherFor {
+            languageVersion.set(JavaLanguageVersion.of(jdkVersion))
+            if (jdkVendor != '') vendor.set(JvmVendorSpec.matching(jdkVendor))
+        }
+
         // Exclude some tests that are not actually tests or do not run cleanly on purpose
         exclude '**/BaseTestBorderStyle.class'
         exclude '**/BaseTestCellUtil.class'
         systemProperties['java.locale.providers'] = 'JRE,CLDR'
 
         doFirst {
-            if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+            if (jdkVersion > 8) {
                 // some options were removed in JDK 18
-                if (JavaVersion.current().ordinal() < JavaVersion.VERSION_18.ordinal()) {
+                if (jdkVersion < 18) {
                     jvmArgs += [
                         '--illegal-access=warn',
                     ]
-                } else {
-                    System.out.println("Configuring for JDK 18 or higher")
                 }
 
                 jvmArgs += [
         ignoreFailures = false
         suppressAnnotations = [ 'org.apache.poi.util.SuppressForbidden' ]
         // forbiddenapis bundled signatures max supported version is 14
-        targetCompatibility = (JavaVersion.VERSION_14.isCompatibleWith(JavaVersion.current()) ? JavaVersion.current() : JavaVersion.VERSION_14)
+        // targetCompatibility = (JavaVersion.VERSION_14.isCompatibleWith(JavaVersion.current()) ? JavaVersion.current() : JavaVersion.VERSION_14)
     }
 
     forbiddenApisMain {

jenkins/create_jobs.groovy

 def defaultSlaves = '(ubuntu)&&!beam&&!cloud-slave&&!H29'
 
 def jdkMapping = [
-        '1.8': 'jdk_1.8_latest',
-        '1.10': 'jdk_10_latest',
-        '1.11': 'jdk_11_latest',
-        '1.12': 'jdk_12_latest',
-        '1.13': 'jdk_13_latest',
-        '1.14': 'jdk_14_latest',
-        '1.15': 'jdk_15_latest',
-        '1.16': 'jdk_16_latest',
-        '1.17': 'jdk_17_latest',
-        '1.18': 'jdk_18_latest',
-        'OpenJDK 1.8': 'adoptopenjdk_hotspot_8u282',
-        'IBMJDK': 'ibmjdk_1.8.0_261',
+        '1.8': [ jenkinsJdk: 'jdk_1.8_latest', jdkVersion: 8, jdkVendor: 'oracle' ],
+        '1.10': [ jenkinsJdk: 'jdk_10_latest', jdkVersion: 10, jdkVendor: 'oracle' ],
+        '1.11': [ jenkinsJdk: 'jdk_11_latest', jdkVersion: 11, jdkVendor: 'oracle' ],
+        '1.12': [ jenkinsJdk: 'jdk_12_latest', jdkVersion: 12, jdkVendor: '' ],
+        '1.13': [ jenkinsJdk: 'jdk_13_latest', jdkVersion: 13, jdkVendor: '' ],
+        '1.14': [ jenkinsJdk: 'jdk_14_latest', jdkVersion: 14, jdkVendor: '' ],
+        '1.15': [ jenkinsJdk: 'jdk_15_latest', jdkVersion: 15, jdkVendor: '' ],
+        '1.16': [ jenkinsJdk: 'jdk_16_latest', jdkVersion: 16, jdkVendor: '' ],
+        '1.17': [ jenkinsJdk: 'jdk_17_latest', jdkVersion: 17, jdkVendor: '' ],
+        '1.18': [ jenkinsJdk: 'jdk_18_latest', jdkVersion: 18, jdkVendor: '' ],
+        'OpenJDK 1.8': [ jenkinsJdk: 'adoptopenjdk_hotspot_8u282', jdkVersion: 8, jdkVendor: 'adoptopenjdk' ],
+        'IBMJDK': [ jenkinsJdk: 'ibmjdk_1.8.0_261', jdkVersion: 8, jdkVendor: 'ibm' ]
 ]
 
 static def shellEx(def context, String cmd, def poijob) {
                 }
             }
         }
-        jdk(jdkMapping.get(jdkKey))
+        jdk(jdkMapping.get(jdkKey).jenkinsJdk)
         scm {
             if (poijob.githubpr) {
                 git {
                     switches('-Dsonar.organization=apache')
                     switches('-Dsonar.projectKey=poi-parent')
                     switches('-Dsonar.host.url=https://sonarcloud.io')
+                    switches('-PjdkVersion=${jdkMapping.get(jdkKey).jdkVersion}')
+                    if (jdkMapping.get(jdkKey).jdkVendor != '') {
+                        switches('-PjdkVendor=${jdkMapping.get(jdkKey).jdkVendor}')
+                    }
                     tasks('clean')
                     tasks('check')
                     tasks('jacocoTestReport')
                         if (poijob.saxonTest) {
                             switches('-Psaxon.test=true')
                         }
+                        switches('-PjdkVersion=${jdkMapping.get(jdkKey).jdkVersion}')
+                        if (jdkMapping.get(jdkKey).jdkVendor != '') {
+                            switches('-PjdkVendor=${jdkMapping.get(jdkKey).jdkVendor}')
+                        }
                     }
                 } else {
                     ant {
                 }
             }
         }
-        jdk(jdkMapping.get(jdkKey))
+        jdk(jdkMapping.get(jdkKey).jenkinsJdk)
         scm {
             svn(xmlbeansSvnBase) { svnNode ->
                 svnNode / browser(class: 'hudson.scm.browsers.ViewSVN') /
                     switches('-Dsonar.organization=apache')
                     switches('-Dsonar.projectKey=apache_xmlbeans')
                     switches('-Dsonar.host.url=https://sonarcloud.io')
+                    switches('-PjdkVersion=${jdkMapping.get(jdkKey).jdkVersion}')
+                    if (jdkMapping.get(jdkKey).jdkVendor != '') {
+                        switches('-PjdkVendor=${jdkMapping.get(jdkKey).jdkVendor}')
+                    }
                 }
                 tasks('clean')
                 tasks('jenkins')

poi-examples/build.gradle

 
 sourceSets {
     main {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(JAVA9_OUT, builtBy: 'cacheJava9')
         }
     }
 task compileJava9(type: JavaCompile) {
     dependsOn 'compileJava', ':poi-ooxml:jar', ':poi-scratchpad:jar'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
+
     destinationDirectory = file(JAVA9_OUT + VERSIONS9)
     source = file(JAVA9_SRC)
     classpath = files()
         '--patch-module', "${MODULE_NAME}=${sourceSets.main.output.classesDirs.asPath}",
         '--module-path', files(MODULE_COMPILE_PATH).asPath
     ]
+
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 task cacheJava9(type: Copy) {
 
     destinationDirectory = file("../build/dist/maven/${project.archivesBaseName}")
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from JAVA9_SRC include '*.class'
         }

poi-excelant/build.gradle

 
 sourceSets {
     main {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(JAVA9_OUT, builtBy: 'cacheJava9')
         }
     }
     test {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(TEST9_OUT, builtBy: 'cacheTest9')
         }
     }
 task compileJava9(type: JavaCompile) {
     dependsOn 'compileJava', ':poi-ooxml:jar', ':poi-scratchpad:jar'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(JAVA9_OUT + VERSIONS9)
     source = file(JAVA9_SRC)
     classpath = files()
         '--patch-module', "${MODULE_NAME}=${sourceSets.main.output.classesDirs.asPath}",
         '--module-path', files(MAIN_MODULE_PATH).asPath
     ]
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 task cacheJava9(type: Copy) {
 task compileTest9(type: JavaCompile) {
     dependsOn 'compileTestJava', ':poi-ooxml:jar', ':poi-scratchpad:jar'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(TEST9_OUT + VERSIONS9)
     source = file(TEST9_SRC)
     options.compilerArgs = [
         '--module-path', files(TEST_MODULE_PATH).asPath
     ]
     classpath = files()
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 
 
     destinationDirectory = file("../build/dist/maven/${project.archivesBaseName}")
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from JAVA9_SRC include '*.class'
         }
     // ignore second module-info.class from main
     duplicatesStrategy = 'exclude'
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from TEST9_SRC include '*.class'
         }
         jvmArgs += [
             "-javaagent:${OOXML_LITE_AGENT}=${OOXML_LITE_REPORT}|${OOXML_LITE_INCLUDES}",
         ]
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             jvmArgs += [
                 '--add-modules', MODULE_NAME,
                 '--module-path', '../build/dist/maven/poi-excelant-tests' + File.pathSeparator + files(TEST_MODULE_PATH).asPath,

poi-integration/build.gradle

 
 sourceSets {
     test {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(TEST9_OUT, builtBy: 'cacheTest9')
         }
         if (IBMVM) {
 final String OOXML_LITE_INCLUDES = "^(com/microsoft/schemas|org/(etsi|openxmlformats|w3/)|org/apache/poi/schemas)"
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_1_8
-    targetCompatibility = JavaVersion.VERSION_1_8
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(jdkVersion))
+        if (jdkVendor != '') vendor.set(JvmVendorSpec.matching(jdkVendor))
+    }
 }
 
 task compileTest9(type: JavaCompile) {
     dependsOn 'compileTestJava', ':poi-ooxml:testJar', ':poi-scratchpad:testJar', ':poi-examples:jar'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(TEST9_OUT + VERSIONS9)
     source = file(TEST9_SRC)
     options.compilerArgs = [
         '--module-path', files(MODULE_COMPILE_PATH).asPath
     ]
     classpath = files()
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 
     // ignore second module-info.class from main
     duplicatesStrategy = 'exclude'
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from TEST9_SRC include '*.class'
         }
         jvmArgs += [
             "-javaagent:${OOXML_LITE_AGENT}=${OOXML_LITE_REPORT}|${OOXML_LITE_INCLUDES}",
         ]
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             jvmArgs += [
                 '--add-modules', MODULE_NAME,
                 '--module-path', '../build/dist/maven/poi-integration-tests' + File.pathSeparator + files(MODULE_RUNTIME_PATH).asPath,

poi-ooxml-full/build.gradle

         // TypeSystemHolder.class is in the resources
         output.dir(BEANS_RES, builtBy: 'generate_beans')
         compileClasspath += files(BEANS_RES)
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(JAVA9_OUT, builtBy: 'cacheJava9')
         }
         java {
 
 compileJava {
     dependsOn 'generate_beans'
+    options.fork = true
+    options.forkOptions.jvmArgs << '-Xmx2G'
 }
 
 task compileJava9(type: JavaCompile) {
     dependsOn 'compileJava'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(JAVA9_OUT + VERSIONS9)
     source = file(JAVA9_SRC)
     classpath = files()
         '--patch-module', "${MODULE_NAME}=${sourceSets.main.output.asPath}",
         '--module-path', files(MAIN_MODULE_PATH).asPath
     ]
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 task cacheJava9(type: Copy) {
 jar {
     dependsOn 'sourceJar'
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from JAVA9_SRC include '*.class'
         }

poi-ooxml-lite-agent/build.gradle

 
 sourceSets {
     main {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(JAVA9_OUT, builtBy: 'cacheJava9')
         }
     }
 final MODULE_NAME = 'org.apache.poi.ooxml_lite'
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_1_8
-    targetCompatibility = JavaVersion.VERSION_1_8
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(jdkVersion))
+        if (jdkVendor != '') vendor.set(JvmVendorSpec.matching(jdkVendor))
+    }
 }
 
 task compileJava9(type: JavaCompile) {
     dependsOn 'compileJava'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(JAVA9_OUT + VERSIONS9)
     source = file(JAVA9_SRC)
     classpath = files()
             '--module-path', sourceSets.main.compileClasspath.asPath
         ]
     }
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 task cacheJava9(type: Copy) {
 jar {
     destinationDirectory = file("../build/dist/maven/${project.archivesBaseName}")
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from JAVA9_SRC include '*.class'
         }

poi-ooxml-lite/build.gradle

 
 sourceSets {
     main {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(JAVA9_OUT, builtBy: 'cacheJava9')
         }
         compileClasspath += files(BEANS_RES)
 
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_1_8
-    targetCompatibility = JavaVersion.VERSION_1_8
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(jdkVersion))
+        if (jdkVendor != '') vendor.set(JvmVendorSpec.matching(jdkVendor))
+    }
+}
+
+compileJava {
+    dependsOn 'compileOoxmlLite'
+    options.fork = true
+    options.forkOptions.jvmArgs << '-Xmx2G'
 }
 
 processResources.dependsOn 'compileOoxmlLite'
-compileJava.dependsOn 'compileOoxmlLite'
 sourcesJar.dependsOn 'compileOoxmlLite'
 
 task compileJava9(type: JavaCompile, dependsOn: 'compileJava') {
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(JAVA9_OUT + VERSIONS9)
     source = file(JAVA9_SRC)
     classpath = files()
             '--module-path', files(MAIN_MODULE_PATH).asPath
         ]
     }
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 task cacheJava9(type: Copy, dependsOn: 'compileJava9') {
         }
     }
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from JAVA9_SRC include '*.class'
         }

poi-ooxml/build.gradle

 configurations {
     runtimeClasspath {
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
 
     compileClasspath {
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
 
 sourceSets {
     main {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(JAVA9_OUT, builtBy: 'cacheJava9')
         }
     }
     test {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(TEST9_OUT, builtBy: 'cacheTest9')
         }
     }
     renderImplementation "org.apache.xmlgraphics:batik-svggen:${batikVersion}"
     renderImplementation("org.apache.xmlgraphics:batik-svgrasterizer:${batikVersion}") {
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
     renderImplementation("org.apache.xmlgraphics:batik-codec:${batikVersion}") {
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
     renderImplementation("org.apache.xmlgraphics:batik-bridge:${batikVersion}") {
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
     rendersignImplementation "org.apache.xmlgraphics:batik-svggen:${batikVersion}"
     rendersignImplementation("org.apache.xmlgraphics:batik-svgrasterizer:${batikVersion}") {
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
     rendersignImplementation("org.apache.xmlgraphics:batik-codec:${batikVersion}") {
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
     rendersignImplementation("org.apache.xmlgraphics:batik-bridge:${batikVersion}") {
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
 
     broken("org.apache.xmlgraphics:batik-script:${batikVersion}"){
         exclude group: 'xalan', module: 'xalan'
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             exclude group: 'xml-apis', module: 'xml-apis'
         }
     }
 task compileJava9(type: JavaCompile) {
     dependsOn 'compileJava', ':poi:jar'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(JAVA9_OUT + VERSIONS9)
     source = file(JAVA9_SRC)
     classpath = files()
         '--patch-module', "${MODULE_NAME}=${sourceSets.main.output.classesDirs.asPath}",
         '--module-path', files(MAIN_MODULE_PATH).asPath
     ]
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 task cacheJava9(type: Copy) {
 task compileTest9(type: JavaCompile) {
     dependsOn 'compileTestJava', ':poi:testJar'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(TEST9_OUT + VERSIONS9)
     source = file(TEST9_SRC)
     options.compilerArgs = [
         '--module-path', files(TEST_MODULE_PATH).asPath
     ]
     classpath = files()
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 
 jar {
     destinationDirectory = file("../build/dist/maven/${project.archivesBaseName}")
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from JAVA9_SRC include '*.class'
         }
     // ignore second module-info.class from main
     duplicatesStrategy = 'exclude'
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from TEST9_SRC include '*.class'
         }
             "-XX:ErrorFile=../build/hs_err_pid%p.log",
             "-javaagent:${OOXML_LITE_AGENT}=${OOXML_LITE_REPORT}|${OOXML_LITE_INCLUDES}"
         ]
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             jvmArgs += [
                 '--add-modules', MODULE_NAME,
                 '--module-path', '../build/dist/maven/poi-ooxml-tests' + File.pathSeparator + files(TEST_MODULE_PATH).asPath,

poi-scratchpad/build.gradle

 
 sourceSets {
     main {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(JAVA9_OUT, builtBy: 'cacheJava9')
         }
     }
     test {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(TEST9_OUT, builtBy: 'cacheTest9')
         }
     }
 task compileJava9(type: JavaCompile) {
     dependsOn 'compileJava', ':poi:jar'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(JAVA9_OUT + VERSIONS9)
     source = file(JAVA9_SRC)
     classpath = files()
         '--patch-module', "${MODULE_NAME}=${sourceSets.main.output.classesDirs.asPath}",
         '--module-path', files(MAIN_MODULE_PATH).asPath
     ]
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 task cacheJava9(type: Copy) {
 task compileTest9(type: JavaCompile) {
     dependsOn 'compileTestJava', ':poi:jar'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
     destinationDirectory = file(TEST9_OUT + VERSIONS9)
     source = file(TEST9_SRC)
     options.compilerArgs = [
         '--module-path', files(TEST_MODULE_PATH).asPath
     ]
     classpath = files()
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 
 jar {
     destinationDirectory = file("../build/dist/maven/${project.archivesBaseName}")
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from JAVA9_SRC include '*.class'
         }
     // ignore second module-info.class from main
     duplicatesStrategy = 'exclude'
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from TEST9_SRC include '*.class'
         }
     systemProperties['junit.jupiter.execution.parallel.enabled'] = 'true'
 
     doFirst {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             jvmArgs += [
                 '--add-modules', MODULE_NAME,
                 '--module-path', '../build/dist/maven/poi-scratchpad-tests' + File.pathSeparator + files(TEST_MODULE_PATH).asPath,

poi/build.gradle

 
 sourceSets {
     main {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(JAVA9_OUT, builtBy: 'cacheJava9')
         }
         java {
         }
     }
     test {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             output.dir(TEST9_OUT, builtBy: 'cacheTest9')
         }
     }
 task compileJava9(type: JavaCompile) {
     dependsOn 'compileJava'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(11)
+    }
     destinationDirectory = file(JAVA9_OUT + VERSIONS9)
     source = file(JAVA9_SRC)
     classpath = files()
 task compileTest9(type: JavaCompile) {
     dependsOn 'compileTestJava'
 
-    sourceCompatibility = 9
-    targetCompatibility = 9
+    javaCompiler = javaToolchains.compilerFor {
+        languageVersion = JavaLanguageVersion.of(jdkVersion)
+        if (jdkVendor != '') vendor = JvmVendorSpec.matching(jdkVendor)
+    }
+
     destinationDirectory = file(TEST9_OUT + VERSIONS9)
     source = file(TEST9_SRC)
     options.compilerArgs = [
         '--module-path', files(MODULE_PATH).asPath
     ]
     classpath = files()
+
+    onlyIf {
+        jdkVersion > 8
+    }
 }
 
 
 jar {
     dependsOn cacheJava9
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from JAVA9_SRC include '*.class'
         }
     // ignore second module-info.class from main
     duplicatesStrategy = 'exclude'
 
-    if (JavaVersion.current() == JavaVersion.VERSION_1_8) {
+    if (jdkVersion == 8) {
         into('META-INF/versions/9') {
             from TEST9_SRC include '*.class'
         }
     systemProperties['junit.jupiter.execution.parallel.enabled'] = 'true'
 
     doFirst {
-        if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
+        if (jdkVersion > 8) {
             jvmArgs << [
                 '--add-modules', MODULE_NAME,
                 '--module-path', '../build/dist/maven/poi-tests' + File.pathSeparator + files(MODULE_PATH).asPath,