java.lang.NullPointerException
   at org.netbeans.api.visual.widget.Widget.calculatePreferredBounds(Widget.java:1017)
   at org.netbeans.api.visual.widget.Widget.getPreferredBounds(Widget.java:987)
   at org.netbeans.modules.uml.drawingarea.layout.HierarchicalLayout$BuildDatastructure.run(HierarchicalLayout.java:231)
   at org.netbeans.modules.uml.drawingarea.layout.HierarchicalLayout$AlgorithmPart.start(HierarchicalLayout.java:157)
   at org.netbeans.modules.uml.drawingarea.layout.HierarchicalLayout.performGraphLayout(HierarchicalLayout.java:174)
   at org.netbeans.api.visual.graph.layout.GraphLayout.layoutGraph(GraphLayout.java:121)
   at org.netbeans.modules.uml.diagrams.options.ElementCustomizationPanel$1.run(ElementCustomizationPanel.java:178)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)
   at java.awt.EventQueue.access$200(EventQueue.java:103)
   at java.awt.EventQueue$3.run(EventQueue.java:694)
   at java.awt.EventQueue$3.run(EventQueue.java:692)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)