我写了一个小的maven插件，一切似乎都适用于maven（2.0.9）的早期版本，但我的版本在版本2.2.1上失败了 堆栈跟踪没有显示我的代码末尾的任何内容，并且想知道是否有人遇到过这个问题。
....
....
[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