PluginDescriptor is null in custom plug-in with M2E

Question

If I run "Update Project..." in Eclipse Mars with M2E 1.6, the PluginDescriptor is null in my custom plug-in.

@Mojo(name = "test", defaultPhase = LifecyclePhase.GENERATE_SOURCES, requiresDependencyResolution = ResolutionScope.COMPILE)
public class TestMojo extends AbstractMojo {

    @Parameter(defaultValue = "${project.build.directory}/generated-sources/test", required = true)
    private File outputDir;

    @Parameter(defaultValue = "${project}", required = true, readonly = true)
    private MavenProject mavenProject;

    @Component
    private PluginDescriptor pluginDescriptor;

    public void execute() throws MojoExecutionException, MojoFailureException {

        mavenProject.addCompileSourceRoot(outputDir.getAbsolutePath());

        pluginDescriptor.getClassRealm();
    }
}

Stacktrace:

org.apache.maven.plugin.PluginExecutionException: Execution run-custom-plugin of goal test-maven-plugin:0.0.1-SNAPSHOT:test failed.
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:145)
at org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:331)
at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1362)
at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:112)
at org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:1360)
at org.eclipse.m2e.core.project.configurator.MojoExecutionBuildParticipant.build(MojoExecutionBuildParticipant.java:52)
at org.eclipse.m2e.core.internal.builder.MavenBuilderImpl.build(MavenBuilderImpl.java:137)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$1.method(MavenBuilder.java:172)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$1.method(MavenBuilder.java:1)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod$1$1.call(MavenBuilder.java:115)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:112)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod$1.call(MavenBuilder.java:105)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:151)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:99)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod.execute(MavenBuilder.java:86)
at org.eclipse.m2e.core.internal.builder.MavenBuilder.build(MavenBuilder.java:200)
at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:734)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:205)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:245)
at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:300)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:303)
at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:359)
at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:382)
at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:144)
at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:235)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
Caused by: java.lang.NullPointerException
at TestMojo.execute(TestMojo.java:300)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
... 31 more

If I run maven build with launch configuration in Eclipse Mars or with mvn in command line it works fine.

Is there a way to get PluginDescriptor for runOnConfiguration?

Answer 1

You should use injected references via expression evaluator like this:

@Parameter(defaultValue = "${plugin}", required=true, readonly = true)
private PluginDescriptor descriptor;