java.lang.NullPointerException
   at org.netbeans.spi.project.ui.support.NodeFactorySupport$DelegateChildren$1.run(NodeFactorySupport.java:204)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:602)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1084)
Caused: org.openide.util.RequestProcessor$FastItem: task failed due to: java.lang.NullPointerException