Question

I have written a Maven plugin abstractor, called maven-base-plugin. This plugin goes over all classes and resources and performs certain tasks. Since it is an abstract plugin, this plugin does not have its packaging set to maven-plugin, but rather “jar”.

I have another plugin, tools-reporter, that using the above plugin API, creates reports for my project. Again, the reports and destinations for the reports are interfaces, so that they could be extended in future. Again, this project has a packaging of “jar”.

Now, I have a third plugin, depending on the reporter plugin generating certain reports for use on artifacts and resources. This plugin has its packaging set to “maven-plugin”. What’s kept me stale for a while now, and various inspections have not solved it, is that I cannot build this third plugin successfully.

When I do, I get:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-plugin-plugin:2.3:descriptor (default-descriptor) on project tools-reporter-sample: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:2.3:descriptor failed: 0 -> [Help 1]

The details say:

org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-plugin-plugin:2.3:descriptor (default-descriptor) on project tools-reporter-sample: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:2.3:descriptor failed: 0
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:225)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    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.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:47)
    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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:120)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-descriptor of goal org.apache.maven.plugins:maven-plugin-plugin:2.3:descriptor failed: 0
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:110)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    ... 25 more
Caused by: java.lang.ArrayIndexOutOfBoundsException: 0
    at org.apache.maven.tools.plugin.extractor.java.JavaMojoDescriptorExtractor.getJavaClass(JavaMojoDescriptorExtractor.java:534)
    at org.apache.maven.tools.plugin.extractor.java.JavaMojoDescriptorExtractor.execute(JavaMojoDescriptorExtractor.java:553)
    at org.apache.maven.tools.plugin.scanner.DefaultMojoScanner.populatePluginDescriptor(DefaultMojoScanner.java:84)
    at org.apache.maven.plugin.plugin.AbstractGeneratorMojo.execute(AbstractGeneratorMojo.java:135)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    ... 26 more

Any help or insight would be much appreciated.

By the way, I have tried various combination of setting packaging to different values. The only thing that works is announcing the third plugin, tools-reporter-sample as a simple “jar”, which is kind of counterproductive, since it eliminates the whole purpose of this exercise.

This is the gist to the offending code:

• https://gist.github.com/3128364

Here is a description of what each of this is for:

• AbstractPluginExecutor.java: The original base plugin that is bundled as a jar and is used by the basic reports plugin
• mave-base-plugin-pom.xml: The pom.xml file for the base maven plugin
• Executor.java: The abstract class that takes care of all the reporting goodness.
• tools-reporter-pom.xml: The pom.xml file for the base report plugin.
• Reporter.java: The sample plugin that is actually supposed to run.
• tools-reporter-sample-pom.xml: The pom.xml file for the sample report plugin.

Answer 1

It turns out that the failure was not due to the plugins hierarchical design at all. But rather strangely, having the plugin include an annotation in its classpath did it. I had a class, @interface Sample {. Once I removed it, everything was solved.

I have not yet figured out why, though.