JPA error (xmlRootContentNode)

java.lang.NullPointerException
at org.eclipse.jpt.core.internal.content.orm.XmlRootContentNode.handleJavaElementChangedEvent(XmlRootContentNode.java:341)
at org.eclipse.jpt.core.internal.JpaFile.handleEvent(JpaFile.java:212)
at org.eclipse.jpt.core.internal.JpaProject.handleEvent(JpaProject.java:647)
at org.eclipse.jpt.core.internal.JpaModel.handleEvent(JpaModel.java:187)
at org.eclipse.jpt.core.internal.JpaModelManager$ElementChangeProcessor.elementChanged(JpaModelManager.java:529)
at org.eclipse.jpt.core.internal.JpaModelManager$ElementChangeListener.elementChanged(JpaModelManager.java:508)
at org.eclipse.jdt.internal.core.DeltaProcessor$3.run(DeltaProcessor.java:1552)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37)
at org.eclipse.jdt.internal.core.DeltaProcessor.notifyListeners(DeltaProcessor.java:1542)
at org.eclipse.jdt.internal.core.DeltaProcessor.firePostChangeDelta(DeltaProcessor.java:1377)
at org.eclipse.jdt.internal.core.DeltaProcessor.fire(DeltaProcessor.java:1353)
at org.eclipse.jdt.internal.core.DeltaProcessor.resourceChanged(DeltaProcessor.java:1916)
at org.eclipse.jdt.internal.core.DeltaProcessingState.resourceChanged(DeltaProcessingState.java:368)
at org.eclipse.core.internal.events.NotificationManager$2.run(NotificationManager.java:282)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37)
at org.eclipse.core.internal.events.NotificationManager.notify(NotificationManager.java:276)
at org.eclipse.core.internal.events.NotificationManager.broadcastChanges(NotificationManager.java:148)
at org.eclipse.core.internal.resources.Workspace.broadcastPostChange(Workspace.java:311)
at org.eclipse.core.internal.resources.Workspace.endOperation(Workspace.java:1018)
at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:150)
at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:235)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)