I wrote a small maven plugin and everything seems to work well with prior version of maven (2.0.9) but my build fails on version 2.2.1 The stack trace does not show anything from my end of the code and was wondering if anyone has encountered this issue.

....
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[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] null
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.NullPointerException
    at java.util.Hashtable.put(Hashtable.java:396)
    at java.util.Properties.setProperty(Properties.java:128)
    at org.apache.maven.project.ModelUtils.cloneProperties(ModelUtils.java:1264)
    at org.apache.maven.project.ModelUtils.cloneModelBaseFields(ModelUtils.java:318)
    at org.apache.maven.project.ModelUtils.cloneModel(ModelUtils.java:953)
    at org.apache.maven.project.DefaultMavenProjectBuilder.calculateConcreteStateInternal(DefaultMavenProjectBuilder.java:1855)
    at org.apache.maven.project.DefaultMavenProjectBuilder.calculateConcreteState(DefaultMavenProjectBuilder.java:1814)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.calculateConcreteState(DefaultLifecycleExecutor.java:779)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:575)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:540)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:519)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:371)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:332)
    at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:181)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:356)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:137)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
    at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:41)
    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:592)
    at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
    at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
    at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
    at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 17 seconds
[INFO] Finished at: Thu May 27 16:18:40 CDT 2010
[INFO] Final Memory: 35M/63M