java.lang.AssertionError: DataNode without FileObject in Lookup
   at org.netbeans.modules.java.api.common.project.ui.ActionFilterNode$ActionFilterChildren.createNodes(ActionFilterNode.java:364)
   at org.netbeans.modules.java.api.common.project.ui.ActionFilterNode$ActionFilterChildren.createNodes(ActionFilterNode.java:348)
   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$Default.getNodes(EntrySupport.java:228)
   at org.openide.nodes.Children.getNodes(Children.java:469)
   at org.openide.nodes.FilterNode$Children$DefaultSupport.updateKeys(FilterNode.java:1699)
   at org.openide.nodes.FilterNode$Children$DefaultSupport.update(FilterNode.java:1686)
   at org.openide.nodes.FilterNode$Children.addNotifyImpl(FilterNode.java:1477)
   at org.openide.nodes.FilterNode$Children.addNotify(FilterNode.java:1470)
   at org.openide.nodes.Children.callAddNotify(Children.java:575)
   at org.openide.nodes.EntrySupport$Default.getArray(EntrySupport.java:770)
   at org.openide.nodes.EntrySupport$Default.getNodes(EntrySupport.java:172)
   at org.openide.nodes.EntrySupport$Default.getNodes(EntrySupport.java:228)
   at org.openide.nodes.EntrySupport$Default.getNodesCount(EntrySupport.java:232)
   at org.openide.nodes.Children.getNodesCount(Children.java:509)
   at org.openide.explorer.view.VisualizerNode.getChildren(VisualizerNode.java:258)
   at org.openide.explorer.view.VisualizerNode.getChildren(VisualizerNode.java:248)
   at org.openide.explorer.view.VisualizerNode.getChildCount(VisualizerNode.java:325)
   at javax.swing.tree.DefaultTreeModel.getChildCount(DefaultTreeModel.java:186)
   at javax.swing.tree.FixedHeightLayoutCache$FHTreeStateNode.expand(FixedHeightLayoutCache.java:1152)
   at javax.swing.tree.FixedHeightLayoutCache.ensurePathIsExpanded(FixedHeightLayoutCache.java:662)
   at javax.swing.tree.FixedHeightLayoutCache.setExpandedState(FixedHeightLayoutCache.java:299)
   at javax.swing.plaf.basic.BasicTreeUI.updateExpandedDescendants(BasicTreeUI.java:1695)
   at javax.swing.plaf.basic.BasicTreeUI$Handler.treeExpanded(BasicTreeUI.java:3783)
   at javax.swing.JTree.fireTreeExpanded(JTree.java:2754)
   at javax.swing.JTree.setExpandedState(JTree.java:3614)
   at javax.swing.JTree.expandPath(JTree.java:2202)
   at javax.swing.plaf.basic.BasicTreeUI.toggleExpandState(BasicTreeUI.java:2264)
   at javax.swing.plaf.basic.BasicTreeUI.handleExpandControlClick(BasicTreeUI.java:2251)
   at javax.swing.plaf.basic.BasicTreeUI.checkForClickInExpandControl(BasicTreeUI.java:2209)
   at javax.swing.plaf.basic.BasicTreeUI$Handler.handleSelection(BasicTreeUI.java:3578)
   at javax.swing.plaf.basic.BasicTreeUI$Handler.mousePressedDND(BasicTreeUI.java:3564)
   at javax.swing.plaf.basic.BasicTreeUI$Handler.mousePressed(BasicTreeUI.java:3523)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:279)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:279)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:279)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:279)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:279)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:279)
   at java.awt.Component.processMouseEvent(Component.java:6502)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
   at java.awt.Component.processEvent(Component.java:6270)
   at java.awt.Container.processEvent(Container.java:2229)
   at java.awt.Component.dispatchEventImpl(Component.java:4861)
   at java.awt.Container.dispatchEventImpl(Container.java:2287)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4832)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4489)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4422)
   at java.awt.Container.dispatchEventImpl(Container.java:2273)
   at java.awt.Window.dispatchEventImpl(Window.java:2713)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
   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.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
   at java.awt.EventQueue$4.run(EventQueue.java:680)
   at java.awt.EventQueue$4.run(EventQueue.java:678)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
   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)