java.lang.NullPointerException
        at org.netbeans.modules.uml.diagrams.nodes.sqd.OperationLabelWidget.updateUI(OperationLabelWidget.java:118)
        at org.netbeans.modules.uml.diagrams.nodes.sqd.OperationLabelWidget.propertyChange(OperationLabelWidget.java:98)
        at org.netbeans.modules.uml.drawingarea.AbstractLabelManager$ConnectionLabelWidget.propertyChange(AbstractLabelManager.java:609)
        at org.netbeans.modules.uml.drawingarea.DrawingAreaChangeHandler.elementChanged(DrawingAreaChangeHandler.java:219)
        at org.netbeans.modules.uml.drawingarea.DrawingAreaEventHandler$1ElementModified.run(DrawingAreaEventHandler.java:211)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)