Test task throws IllegalArgumentException whithout error message

Old Forum
1

Executing “test” in my project “prima-migration” leads to an IllegalArgumentException (see Stacktrace). The Exception is thrown after all tests were executed and the test result report was written to \build\reports\tests. Other projects can be successfully built, I think it has something to do with the project files.

Any ideas about the cause of this exception? How can I track down the cause of this exception? (Using --debug does not help - there is not other error or warn entry than the stacktrace).

org.gradle.api.tasks.TaskExecutionException: Execution failed for task ‘:prima-migration:test’.

at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:68)

at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)

at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:34)

at org.gradle.api.internal.changedetection.CacheLockHandlingTaskExecuter$1.run(CacheLockHandlingTaskExecuter.java:34)

at org.gradle.cache.internal.DefaultCacheAccess$2.create(DefaultCacheAccess.java:200)

at org.gradle.cache.internal.DefaultCacheAccess.longRunningOperation(DefaultCacheAccess.java:172)

at org.gradle.cache.internal.DefaultCacheAccess.longRunningOperation(DefaultCacheAccess.java:198)

at org.gradle.cache.internal.DefaultPersistentDirectoryStore.longRunningOperation(DefaultPersistentDirectoryStore.java:111)

at org.gradle.api.internal.changedetection.DefaultTaskArtifactStateCacheAccess.longRunningOperation(DefaultTaskArtifactStateCacheAccess.java:83)

at org.gradle.api.internal.changedetection.CacheLockHandlingTaskExecuter.execute(CacheLockHandlingTaskExecuter.java:32)

at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:55)

at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:57)

at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:41)

at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:51)

at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:52)

at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:42)

at org.gradle.api.internal.AbstractTask.executeWithoutThrowingTaskFailure(AbstractTask.java:247)

at org.gradle.execution.DefaultTaskGraphExecuter.executeTask(DefaultTaskGraphExecuter.java:192)

at org.gradle.execution.DefaultTaskGraphExecuter.doExecute(DefaultTaskGraphExecuter.java:177)

at org.gradle.execution.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:83)

at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:36)

at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)

at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExecuter.java:23)

at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecuter.java:67)

at org.gradle.api.internal.changedetection.TaskCacheLockHandlingBuildExecuter$1.run(TaskCacheLockHandlingBuildExecuter.java:31)

at org.gradle.cache.internal.DefaultCacheAccess$1.create(DefaultCacheAccess.java:111)

at org.gradle.cache.internal.DefaultCacheAccess.useCache(DefaultCacheAccess.java:126)

at org.gradle.cache.internal.DefaultCacheAccess.useCache(DefaultCacheAccess.java:109)

at org.gradle.cache.internal.DefaultPersistentDirectoryStore.useCache(DefaultPersistentDirectoryStore.java:103)

at org.gradle.api.internal.changedetection.DefaultTaskArtifactStateCacheAccess.useCache(DefaultTaskArtifactStateCacheAccess.java:79)

at org.gradle.api.internal.changedetection.TaskCacheLockHandlingBuildExecuter.execute(TaskCacheLockHandlingBuildExecuter.java:29)

at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)

at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExecuter.java:23)

at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecuter.java:67)

at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)

at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)

at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:54)

at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:155)

at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:110)

at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:78)

at org.gradle.launcher.cli.RunBuildAction.execute(RunBuildAction.java:42)

at org.gradle.launcher.cli.RunBuildAction.execute(RunBuildAction.java:28)

at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:201)

at org.gradle.launcher.cli.CommandLineActionFactory$ParseAndBuildAction.execute(CommandLineActionFactory.java:174)

at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:170)

at org.gradle.launcher.cli.CommandLineActionFactory$WithLogging.execute(CommandLineActionFactory.java:139)

at org.gradle.launcher.exec.ExceptionReportingAction.execute(ExceptionReportingAction.java:31)

at org.gradle.launcher.exec.ExceptionReportingAction.execute(ExceptionReportingAction.java:20)

at org.gradle.launcher.Main.doAction(Main.java:48)

at org.gradle.launcher.exec.EntryPoint.run(EntryPoint.java:45)

at org.gradle.launcher.Main.main(Main.java:39)

at org.gradle.launcher.ProcessBootstrap.runNoExit(ProcessBootstrap.java:50)

at org.gradle.launcher.ProcessBootstrap.run(ProcessBootstrap.java:32)

at org.gradle.launcher.GradleMain.main(GradleMain.java:24)

Caused by: java.lang.IllegalArgumentException

at org.gradle.util.JarUtil.extractZipEntry(JarUtil.java:41)

at org.gradle.api.internal.tasks.testing.detection.ClassFileExtractionManager.extractClassFile(ClassFileExtractionManager.java:105)

at org.gradle.api.internal.tasks.testing.detection.ClassFileExtractionManager.getLibraryClassFile(ClassFileExtractionManager.java:79)

at org.gradle.api.internal.tasks.testing.detection.AbstractTestFrameworkDetector.getSuperTestClassFile(AbstractTestFrameworkDetector.java:80)

at org.gradle.api.internal.tasks.testing.junit.JUnitDetector.processTestClass(JUnitDetector.java:52)

at org.gradle.api.internal.tasks.testing.detection.AbstractTestFrameworkDetector.processTestClass(AbstractTestFrameworkDetector.java:120)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestClassScanner$1.visitClassFile(DefaultTestClassScanner.java:58)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestClassScanner$ClassFileVisitor.visitFile(DefaultTestClassScanner.java:78)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:151)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.visit(DirectoryFileTree.java:119)

at org.gradle.api.internal.file.collections.FileTreeAdapter.visit(FileTreeAdapter.java:96)

at org.gradle.api.internal.file.CompositeFileTree.visit(CompositeFileTree.java:54)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestClassScanner.detectionScan(DefaultTestClassScanner.java:56)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestClassScanner.run(DefaultTestClassScanner.java:50)

at org.gradle.api.internal.tasks.testing.processors.TestMainAction.run(TestMainAction.java:43)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestExecuter.execute(DefaultTestExecuter.java:75)

at org.gradle.api.internal.BeanDynamicObject$MetaClassAdapter.invokeMethod(BeanDynamicObject.java:196)

at org.gradle.api.internal.BeanDynamicObject.invokeMethod(BeanDynamicObject.java:102)

at org.gradle.api.internal.CompositeDynamicObject.invokeMethod(CompositeDynamicObject.java:99)

at org.gradle.api.tasks.testing.Test_Decorated.invokeMethod(Unknown Source)

at org.gradle.util.ReflectionUtil.invoke(ReflectionUtil.groovy:23)

at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$4.execute(AnnotationProcessingTaskFactory.java:150)

at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$4.execute(AnnotationProcessingTaskFactory.java:145)

at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:477)

at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:466)

at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:60)

… 53 more

2

Looks weird. Which Gradle version? Please post output of running with ‘–full-stacktrace’.

3

We are using Milestone-9, but the same problem appears with RC-3 as well. The full stack trace is:

FAILURE: Build failed with an exception.

  • What went wrong: Execution failed for task ‘:prima-migration:test’. > java.lang.IllegalArgumentException (no error message)

  • Try: Run with --info or --debug option to get more log output.

  • Exception is: org.gradle.api.tasks.TaskExecutionException: Execution failed for task ‘:prima-migration:test’.

at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:68)

at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:46)

at org.gradle.api.internal.tasks.execution.PostExecutionAnalysisTaskExecuter.execute(PostExecutionAnalysisTaskExecuter.java:34)

at org.gradle.api.internal.changedetection.CacheLockHandlingTaskExecuter$1.run(CacheLockHandlingTaskExecuter.java:34)

at org.gradle.cache.internal.DefaultCacheAccess$2.create(DefaultCacheAccess.java:200)

at org.gradle.cache.internal.DefaultCacheAccess.longRunningOperation(DefaultCacheAccess.java:172)

at org.gradle.cache.internal.DefaultCacheAccess.longRunningOperation(DefaultCacheAccess.java:198)

at org.gradle.cache.internal.DefaultPersistentDirectoryStore.longRunningOperation(DefaultPersistentDirectoryStore.java:111)

at org.gradle.api.internal.changedetection.DefaultTaskArtifactStateCacheAccess.longRunningOperation(DefaultTaskArtifactStateCacheAccess.java:83)

at org.gradle.api.internal.changedetection.CacheLockHandlingTaskExecuter.execute(CacheLockHandlingTaskExecuter.java:32)

at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:55)

at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:57)

at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:41)

at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:51)

at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:52)

at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:42)

at org.gradle.api.internal.AbstractTask.executeWithoutThrowingTaskFailure(AbstractTask.java:247)

at org.gradle.execution.DefaultTaskGraphExecuter.executeTask(DefaultTaskGraphExecuter.java:192)

at org.gradle.execution.DefaultTaskGraphExecuter.doExecute(DefaultTaskGraphExecuter.java:177)

at org.gradle.execution.DefaultTaskGraphExecuter.execute(DefaultTaskGraphExecuter.java:83)

at org.gradle.execution.SelectedTaskExecutionAction.execute(SelectedTaskExecutionAction.java:36)

at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)

at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExecuter.java:23)

at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecuter.java:67)

at org.gradle.api.internal.changedetection.TaskCacheLockHandlingBuildExecuter$1.run(TaskCacheLockHandlingBuildExecuter.java:31)

at org.gradle.cache.internal.DefaultCacheAccess$1.create(DefaultCacheAccess.java:111)

at org.gradle.cache.internal.DefaultCacheAccess.useCache(DefaultCacheAccess.java:126)

at org.gradle.cache.internal.DefaultCacheAccess.useCache(DefaultCacheAccess.java:109)

at org.gradle.cache.internal.DefaultPersistentDirectoryStore.useCache(DefaultPersistentDirectoryStore.java:103)

at org.gradle.api.internal.changedetection.DefaultTaskArtifactStateCacheAccess.useCache(DefaultTaskArtifactStateCacheAccess.java:79)

at org.gradle.api.internal.changedetection.TaskCacheLockHandlingBuildExecuter.execute(TaskCacheLockHandlingBuildExecuter.java:29)

at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)

at org.gradle.execution.DefaultBuildExecuter.access$200(DefaultBuildExecuter.java:23)

at org.gradle.execution.DefaultBuildExecuter$2.proceed(DefaultBuildExecuter.java:67)

at org.gradle.execution.DryRunBuildExecutionAction.execute(DryRunBuildExecutionAction.java:32)

at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:61)

at org.gradle.execution.DefaultBuildExecuter.execute(DefaultBuildExecuter.java:54)

at org.gradle.initialization.DefaultGradleLauncher.doBuildStages(DefaultGradleLauncher.java:155)

at org.gradle.initialization.DefaultGradleLauncher.doBuild(DefaultGradleLauncher.java:110)

at org.gradle.initialization.DefaultGradleLauncher.run(DefaultGradleLauncher.java:78)

at org.gradle.launcher.cli.RunBuildAction.execute(RunBuildAction.java:42)

at org.gradle.launcher.cli.RunBuildAction.execute(RunBuildAction.java:28)

at org.gradle.launcher.exec.ExceptionReportingAction.execute(ExceptionReportingAction.java:32)

at org.gradle.launcher.exec.ExceptionReportingAction.execute(ExceptionReportingAction.java:21)

at org.gradle.launcher.cli.CommandLineActionFactory$WithLoggingAction.execute(CommandLineActionFactory.java:302)

at org.gradle.launcher.cli.CommandLineActionFactory$WithLoggingAction.execute(CommandLineActionFactory.java:286)

at org.gradle.launcher.Main.doAction(Main.java:48)

at org.gradle.launcher.exec.EntryPoint$1.execute(EntryPoint.java:53)

at org.gradle.launcher.exec.EntryPoint$1.execute(EntryPoint.java:51)

at org.gradle.launcher.exec.Execution.execute(Execution.java:28)

at org.gradle.launcher.exec.EntryPoint.run(EntryPoint.java:39)

at org.gradle.launcher.Main.main(Main.java:39)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

at java.lang.reflect.Method.invoke(Method.java:597)

at org.gradle.launcher.ProcessBootstrap.runNoExit(ProcessBootstrap.java:51)

at org.gradle.launcher.ProcessBootstrap.run(ProcessBootstrap.java:33)

at org.gradle.launcher.GradleMain.main(GradleMain.java:24)

Caused by: java.lang.IllegalArgumentException

at java.util.zip.ZipInputStream.getUTF8String(ZipInputStream.java:317)

at java.util.zip.ZipInputStream.getFileName(ZipInputStream.java:436)

at java.util.zip.ZipInputStream.readLOC(ZipInputStream.java:255)

at java.util.zip.ZipInputStream.getNextEntry(ZipInputStream.java:82)

at org.gradle.util.JarUtil.extractZipEntry(JarUtil.java:41)

at org.gradle.api.internal.tasks.testing.detection.ClassFileExtractionManager.extractClassFile(ClassFileExtractionManager.java:105)

at org.gradle.api.internal.tasks.testing.detection.ClassFileExtractionManager.getLibraryClassFile(ClassFileExtractionManager.java:79)

at org.gradle.api.internal.tasks.testing.detection.AbstractTestFrameworkDetector.getSuperTestClassFile(AbstractTestFrameworkDetector.java:80)

at org.gradle.api.internal.tasks.testing.junit.JUnitDetector.processTestClass(JUnitDetector.java:52)

at org.gradle.api.internal.tasks.testing.detection.AbstractTestFrameworkDetector.processTestClass(AbstractTestFrameworkDetector.java:120)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestClassScanner$1.visitClassFile(DefaultTestClassScanner.java:58)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestClassScanner$ClassFileVisitor.visitFile(DefaultTestClassScanner.java:78)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:151)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.walkDir(DirectoryFileTree.java:166)

at org.gradle.api.internal.file.collections.DirectoryFileTree.visit(DirectoryFileTree.java:119)

at org.gradle.api.internal.file.collections.FileTreeAdapter.visit(FileTreeAdapter.java:96)

at org.gradle.api.internal.file.CompositeFileTree.visit(CompositeFileTree.java:54)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestClassScanner.detectionScan(DefaultTestClassScanner.java:56)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestClassScanner.run(DefaultTestClassScanner.java:50)

at org.gradle.api.internal.tasks.testing.processors.TestMainAction.run(TestMainAction.java:43)

at org.gradle.api.internal.tasks.testing.detection.DefaultTestExecuter.execute(DefaultTestExecuter.java:75)

at org.gradle.api.tasks.testing.Test.executeTests(Test.java:395)

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

at java.lang.reflect.Method.invoke(Method.java:597)

at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:90)

at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:233)

at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1047)

at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:877)

at org.gradle.api.internal.BeanDynamicObject$MetaClassAdapter.invokeMethod(BeanDynamicObject.java:196)

at org.gradle.api.internal.BeanDynamicObject.invokeMethod(BeanDynamicObject.java:102)

at org.gradle.api.internal.CompositeDynamicObject.invokeMethod(CompositeDynamicObject.java:99)

at org.gradle.api.tasks.testing.Test_Decorated.invokeMethod(Unknown Source)

at groovy.lang.GroovyObject$invokeMethod.call(Unknown Source)

at org.gradle.util.ReflectionUtil.invoke(ReflectionUtil.groovy:23)

at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$4.execute(AnnotationProcessingTaskFactory.java:150)

at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$4.execute(AnnotationProcessingTaskFactory.java:145)

at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:477)

at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:466)

at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:60)

… 58 more

4

Maybe, the problem is related to an old java bug: "IllegalArgumentException in ZipInputStream while reading unicode file " - http://bugs.sun.com/view_bug.do?bug_id=4532049

Running the following test program with a ZIP file containing an entry with umlauts, an IllegalArgumentException is thrown.

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
  public final class ZipUmlauts {
      public static void main(String[] args) throws IOException {
        FileInputStream fis=new FileInputStream("umlauts.zip");
        ZipInputStream zis=new ZipInputStream(fis);
        ZipEntry ze;
        while ((ze=zis.getNextEntry())!=null) {
            System.out.println(ze.getName());
        }
    }
}

I ran the test program with all four *.jar files in /build/libs folder. There were no exceptions.

Which other JAR or ZIP file does the DefaultTestClassScanner examine?

5

My best guess is that one of the Jars on the class path uses an encoding other than UTF-8 for filenames and/or comments, which is only supported from JDK7 onwards. Can you try to run Gradle with JDK7, e.g. by setting ‘JAVA_HOME’ accordingly?

6

Your guess ist correct. One of the jars contains files with Umlauts (i.e. AaAumlautä.class). I also assume, that using JDK7 would help. Unfortunately this is not option in our project.

I noticed that when I build the same project with maven, the resulting JAR file does not contain the class with with an umlaut:

Our solution was to use mavens JAR builder instead of gradles. A rudimentary draft:

// add external jar dependency
buildscript {
 repositories {
        maven {
         url '...'
        }
        mavenLocal()
 }
 dependencies {
  classpath group: 'org.codehaus.plexus', name: 'plexus-archiver', version: '2.0'
 }
}
  // import JarArchiver
import org.codehaus.plexus.archiver.jar.JarArchiver
  // modify jar task
jar << {
 JarArchiver archiver = new JarArchiver();
 inputs.files.each { file ->
  String relativeFilename = getRelativeFilename(file);
  if (relativeFilename != null) {
   archiver.addFile(file, relativeFilename)
  }
 }
    archiver.setDestFile(outputs.files.getSingleFile())
 archiver.createArchive();
}