java.lang.AssertionError: DataNode without FileObject in Lookup
   at org.netbeans.modules.apisupport.project.ui.ActionFilterNode$ActionFilterChildren.createNodes(ActionFilterNode.java:176)
   at org.netbeans.modules.apisupport.project.ui.ActionFilterNode$ActionFilterChildren.createNodes(ActionFilterNode.java:160)
   at org.openide.nodes.Children$Keys$KE.nodes(Children.java:1661)
   at org.openide.nodes.ChildrenArray.nodesFor(ChildrenArray.java:149)
   at org.openide.nodes.EntrySupport$Default$Info.nodes(EntrySupport.java:943)
   at org.openide.nodes.EntrySupport$Default.justComputeNodes(EntrySupport.java:253)
   at org.openide.nodes.ChildrenArray.nodes(ChildrenArray.java:88)
   at org.openide.nodes.EntrySupport$Default.getNodes(EntrySupport.java:183)
   at org.openide.nodes.EntrySupport$Default.createSnapshot(EntrySupport.java:159)
   at org.openide.nodes.FilterNode$Children$DefaultSupport.createSnapshot(FilterNode.java:1642)
   at org.openide.nodes.FilterNode$Children$DefaultSupport.createSnapshot(FilterNode.java:1643)
   at org.openide.nodes.FilterNode$Children$DefaultSupport.createSnapshot(FilterNode.java:1643)
   at org.openide.nodes.EntrySupport$Default.snapshot(EntrySupport.java:152)
   at org.openide.nodes.Children.snapshot(Children.java:532)
   at org.openide.explorer.view.VisualizerNode$1.run(VisualizerNode.java:277)
   at org.openide.explorer.view.VisualizerNode$1.run(VisualizerNode.java:275)
   at org.openide.util.Mutex.readAccess(Mutex.java:330)
   at org.openide.util.Mutex$1R.run(Mutex.java:1305)
   at org.openide.util.Mutex.doWrapperAccess(Mutex.java:1324)
   at org.openide.util.Mutex.readAccess(Mutex.java:278)
   at org.openide.explorer.view.VisualizerNode.getChildren(VisualizerNode.java:274)
   at org.openide.explorer.view.VisualizerNode.getChildren(VisualizerNode.java:248)
   at org.openide.explorer.view.VisualizerNode.getChildCount(VisualizerNode.java:325)
   at javax.swing.tree.DefaultTreeModel.getChildCount(DefaultTreeModel.java:186)
   at javax.swing.plaf.basic.BasicTreeUI.paintExpandControl(BasicTreeUI.java:1487)
   at javax.swing.plaf.basic.BasicTreeUI.paint(BasicTreeUI.java:1219)
   at javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
   at javax.swing.JComponent.paintComponent(JComponent.java:778)
   at javax.swing.JComponent.paint(JComponent.java:1054)
   at org.openide.explorer.view.TreeView$ExplorerTree.access$1301(TreeView.java:1734)
   at org.openide.explorer.view.TreeView$ExplorerTree.guardedPaint(TreeView.java:1876)
   at org.openide.explorer.view.TreeView$ExplorerTree.access$1600(TreeView.java:1734)
   at org.openide.explorer.view.TreeView$ExplorerTree$GuardedActions.run(TreeView.java:2198)
   at org.openide.util.Mutex.readAccess(Mutex.java:330)
   at org.openide.util.Mutex$1R.run(Mutex.java:1305)
   at org.openide.nodes.Children$ProjectManagerDeadlockDetector.execute(Children.java:1920)
   at org.openide.util.Mutex.doWrapperAccess(Mutex.java:1326)
   at org.openide.util.Mutex.readAccess(Mutex.java:278)
   at org.openide.explorer.view.TreeView$ExplorerTree$GuardedActions.<init>(TreeView.java:2190)
   at org.openide.explorer.view.TreeView$ExplorerTree.paint(TreeView.java:1847)
   at javax.swing.JComponent.paintChildren(JComponent.java:887)
   at javax.swing.JComponent.paint(JComponent.java:1063)
   at javax.swing.JViewport.paint(JViewport.java:725)
   at javax.swing.JComponent.paintChildren(JComponent.java:887)
   at javax.swing.JComponent.paint(JComponent.java:1063)
   at javax.swing.JComponent.paintChildren(JComponent.java:887)
   at javax.swing.JComponent.paint(JComponent.java:1063)
   at javax.swing.JComponent.paintChildren(JComponent.java:887)
   at javax.swing.JComponent.paint(JComponent.java:1063)
   at javax.swing.JComponent.paintChildren(JComponent.java:887)
   at javax.swing.JComponent.paint(JComponent.java:1063)
   at org.netbeans.swing.tabcontrol.TabbedContainer.paint(TabbedContainer.java:973)
   at javax.swing.JComponent.paintChildren(JComponent.java:887)
   at javax.swing.JComponent.paint(JComponent.java:1063)
   at javax.swing.JComponent.paintToOffscreen(JComponent.java:5221)
   at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1482)
   at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1413)
   at javax.swing.RepaintManager.paint(RepaintManager.java:1206)
   at javax.swing.JComponent._paintImmediately(JComponent.java:5169)
   at javax.swing.JComponent.paintImmediately(JComponent.java:4980)
   at javax.swing.JComponent.paintImmediately(JComponent.java:4961)
   at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:770)
   at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:728)
   at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:677)
   at javax.swing.RepaintManager.access$700(RepaintManager.java:59)
   at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1621)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:705)
   at java.awt.EventQueue.access$000(EventQueue.java:101)
   at java.awt.EventQueue$3.run(EventQueue.java:666)
   at java.awt.EventQueue$3.run(EventQueue.java:664)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:675)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:158)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)