java.util.ConcurrentModificationException
   at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
   at java.util.ArrayList$Itr.next(ArrayList.java:851)
   at org.openide.util.actions.CookieAction$CookieDelegateAction.detachListeners(CookieAction.java:402)
   at org.openide.util.actions.CookieAction$CookieDelegateAction.setNodes(CookieAction.java:382)
   at org.openide.util.actions.CookieAction$CookieDelegateAction.resultChanged(CookieAction.java:345)
   at sun.reflect.GeneratedMethodAccessor36.invoke(GeneratedMethodAccessor36.java:0)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:497)
   at org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:461)
   at com.sun.proxy.$Proxy6.resultChanged(.java:0)
   at org.openide.util.lookup.AbstractLookup$NotifyListeners.run(AbstractLookup.java:542)
   at org.openide.util.lookup.AbstractLookup.notifyIn(AbstractLookup.java:314)
   at org.openide.util.lookup.AbstractLookup.removePairImpl(AbstractLookup.java:288)
   at org.openide.util.lookup.AbstractLookup.removePair(AbstractLookup.java:271)
   at org.openide.util.lookup.AbstractLookup$Content.removePair(AbstractLookup.java:1294)
   at org.openide.util.lookup.InstanceContent.remove(InstanceContent.java:116)
   at org.netbeans.modules.java.navigation.ClassMemberPanelUI$7.run(ClassMemberPanelUI.java:776)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1423)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)