java.lang.NullPointerException
        at org.netbeans.modules.java.project.BrokenReferencesModel.getReferences(BrokenReferencesModel.java:280)
        at org.netbeans.modules.java.project.BrokenReferencesModel.isBroken(BrokenReferencesModel.java:180)
        at org.netbeans.spi.java.project.support.ui.BrokenReferencesSupport.isBroken(BrokenReferencesSupport.java:115)
        at org.netbeans.modules.java.j2seproject.ui.J2SELogicalViewProvider.hasBrokenLinks(J2SELogicalViewProvider.java:196)
        at org.netbeans.modules.java.j2seproject.J2SEProject$ProjectOpenedHookImpl.projectOpened(J2SEProject.java:579)
        at org.netbeans.spi.project.ui.ProjectOpenedHook$1.projectOpened(ProjectOpenedHook.java:81)
        at org.netbeans.spi.project.ui.support.UILookupMergerSupport$OpenHookImpl.projectOpened(UILookupMergerSupport.java:193)
        at org.netbeans.spi.project.ui.ProjectOpenedHook$1.projectOpened(ProjectOpenedHook.java:81)
        at org.netbeans.modules.project.ui.OpenProjectList.notifyOpened(OpenProjectList.java:956)
        at org.netbeans.modules.project.ui.OpenProjectList.doOpenProject(OpenProjectList.java:1004)
        at org.netbeans.modules.project.ui.OpenProjectList.doOpen(OpenProjectList.java:603)
        at org.netbeans.modules.project.ui.OpenProjectList.access$1100(OpenProjectList.java:123)
        at org.netbeans.modules.project.ui.OpenProjectList$3.run(OpenProjectList.java:493)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:561)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:986)