java.lang.NullPointerException
        at org.netbeans.spi.java.project.support.ui.PackageViewChildren.refreshKeys(PackageViewChildren.java:245)
        at org.netbeans.spi.java.project.support.ui.PackageViewChildren.findChild(PackageViewChildren.java:205)
        at org.openide.nodes.FilterNode$Children.findChild(FilterNode.java:1381)
        at org.openide.nodes.FilterNode$Children.findChild(FilterNode.java:1381)
        at org.openide.nodes.FilterNode$Children.findChild(FilterNode.java:1381)
        at org.openide.nodes.NodeOp.findChild(NodeOp.java:257)
        at org.openide.nodes.NodeOp.findPath(NodeOp.java:275)
        at org.openide.nodes.NodeOp.findPath(NodeOp.java:305)
        at org.netbeans.spi.java.project.support.ui.PackageRootNode$PathFinder.findPath(PackageRootNode.java:400)
        at org.netbeans.spi.java.project.support.ui.PackageView.findPath(PackageView.java:116)
        at org.netbeans.modules.java.j2seproject.ui.J2SELogicalViewProvider.findPath(J2SELogicalViewProvider.java:168)
        at org.netbeans.modules.project.ui.ProjectsRootNode.findNode(ProjectsRootNode.java:169)
        at org.netbeans.modules.project.ui.ProjectTab.selectNode(ProjectTab.java:429)
        at org.netbeans.modules.project.ui.ProjectUtilities$3$1.run(ProjectUtilities.java:282)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)