java.util.ConcurrentModificationException
   at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
   at java.util.AbstractList$Itr.remove(AbstractList.java:357)
   at org.netbeans.modules.xml.sync.DataObjectSyncSupport.addRepresentation(DataObjectSyncSupport.java:142)
   at org.netbeans.modules.xml.text.TextEditorSupport$3.stateChanged(TextEditorSupport.java:204)
   at org.openide.text.CloneableEditorSupport.fireStateChangeEvent(CloneableEditorSupport.java:2370)
   at org.openide.text.CloneableEditorSupport.fireDocumentChange(CloneableEditorSupport.java:2353)
   at org.openide.text.CloneableEditorSupport.access$900(CloneableEditorSupport.java:133)
   at org.openide.text.CloneableEditorSupport$3.doRun(CloneableEditorSupport.java:689)
   at org.openide.text.CloneableEditorSupport$3.run(CloneableEditorSupport.java:677)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)