Simplified example of Gradle plugin ClassLoading issue. The real issue can be seen in pivotalsoftware/pivotal-cla/tree/bug-staging

• Clone the project

• Install the plugin

  $ cd plugin
  $ ./gradlew install

• Use the plugin

  $ cd ../useplugin
  $ ./gradlew bug --stacktrace
  :bug FAILED
  
  FAILURE: Build failed with an exception.
  
  * What went wrong:
  Execution failed for task ':bug'.
  > No signature of method: org.cloudfoundry.gradle.tasks.ServiceCloudFoundryHelper$_createServices_closure1.doCall() is applicable for argument types: (org.cloudfoundry.gradle.CloudFoundryServiceExtension) values: [org.cloudfoundry.gradle.CloudFoundryServiceExtension@81c5da9]
    Possible solutions: doCall(org.cloudfoundry.gradle.CloudFoundryServiceExtension), findAll(), findAll(), isCase(java.lang.Object), isCase(java.lang.Object)
    The following classes appear as argument class and as parameter class, but are defined by different class loader:
    org.cloudfoundry.gradle.CloudFoundryServiceExtension (defined by 'org.gradle.api.internal.initialization.loadercache.DefaultClassLoaderCache$HashedMutableURLClassLoader@585427e' and 'org.gradle.api.internal.initialization.loadercache.DefaultClassLoaderCache$HashedMutableURLClassLoader@4b1c84a9')
    If one of the method suggestions matches the method you wanted to call,
    then check your class loader setup.
  
  * Try:
  Run with --info or --debug option to get more log output.
  
  * Exception is:
  org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':bug'.
  	...
  Caused by: groovy.lang.MissingMethodException: No signature of method: org.cloudfoundry.gradle.tasks.ServiceCloudFoundryHelper$_createServices_closure1.doCall() is applicable for argument types: (org.cloudfoundry.gradle.CloudFoundryServiceExtension) values: [org.cloudfoundry.gradle.CloudFoundryServiceExtension@81c5da9]
  Possible solutions: doCall(org.cloudfoundry.gradle.CloudFoundryServiceExtension), findAll(), findAll(), isCase(java.lang.Object), isCase(java.lang.Object)
  The following classes appear as argument class and as parameter class, but are defined by different class loader:
  org.cloudfoundry.gradle.CloudFoundryServiceExtension (defined by 'org.gradle.api.internal.initialization.loadercache.DefaultClassLoaderCache$HashedMutableURLClassLoader@585427e' and 'org.gradle.api.internal.initialization.loadercache.DefaultClassLoaderCache$HashedMutableURLClassLoader@4b1c84a9')
  If one of the method suggestions matches the method you wanted to call,
  then check your class loader setup.
  	at org.cloudfoundry.gradle.tasks.ServiceCloudFoundryHelper.createServices(ServiceCloudFoundryHelper.groovy:23)
  	at org.cloudfoundry.gradle.tasks.CreateServiceCloudFoundryTask$_createService_closure1.doCall(CreateServiceCloudFoundryTask.groovy:46)
  	at org.cloudfoundry.gradle.tasks.CreateServiceCloudFoundryTask.withCloudFoundryClient(CreateServiceCloudFoundryTask.groovy:36)
  	at org.cloudfoundry.gradle.tasks.CreateServiceCloudFoundryTask.createService(CreateServiceCloudFoundryTask.groovy:45)
  	at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:75)
  	at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.doExecute(AnnotationProcessingTaskFactory.java:228)
  	at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:221)
  	at org.gradle.api.internal.project.taskfactory.AnnotationProcessingTaskFactory$StandardTaskAction.execute(AnnotationProcessingTaskFactory.java:210)
  	at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:585)
  	at org.gradle.api.internal.AbstractTask$TaskActionWrapper.execute(AbstractTask.java:568)
  	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:80)
  	at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:61)
  	... 68 more

These are some workarounds, but unfortunately it doesn’t help with my original issue.

• https://github.com/rwinch/gradle-buildscript-question/tree/fix-matching-classpath

• https://github.com/rwinch/gradle-buildscript-question/tree/fix-plugin-class