When I tried to use the cobertura plugin for hudson in conjunction with the maven2 plugin, I got this
error on hudson :

[INFO] ------------------------------------------------------------------------
[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] null
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.NullPointerException
at hudson.plugins.cobertura.CoberturaProjectAction.<init>(CoberturaProjectAction.java:27)
at
hudson.plugins.cobertura.MavenCoberturaPublisher.getProjectAction(MavenCoberturaPublisher.java:19
8)
at hudson.maven.MavenModule.addTransientActionsFromBuild(MavenModule.java:373)
at hudson.maven.MavenModule.addTransientActionsFromBuild(MavenModule.java:45)
at hudson.maven.AbstractMavenProject.updateTransientActions(AbstractMavenProject.java:33)
at hudson.maven.MavenModuleSet.updateTransientActions(MavenModuleSet.java:149)
at hudson.maven.MavenModuleSetBuild.notifyModuleBuild(MavenModuleSetBuild.java:257)
at hudson.maven.MavenBuild$ProxyImpl2.end(MavenBuild.java:348)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at
hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:240)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:223)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:183)
at hudson.remoting.UserRequest.perform(UserRequest.java:69)
at hudson.remoting.UserRequest.perform(UserRequest.java:23)
at hudson.remoting.Request$2.run(Request.java:206)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
at java.lang.Thread.run(Thread.java:619)