java.lang.ClassCastException: java.net.URL cannot be cast to org.openide.loaders.DataObject
   at org.netbeans.modules.editor.hints.HintsControllerImpl.setErrors(HintsControllerImpl.java:93)
   at org.netbeans.spi.editor.hints.HintsController$1.run(HintsController.java:84)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)