java.lang.IllegalArgumentException: Task: org.netbeans.modules.java.editor.fold.JavaElementFoldManager$JavaElementFoldTask@b5b58a is already scheduled
   at org.netbeans.modules.java.source.JavaSourceAccessor.addPhaseCompletionTask(JavaSourceAccessor.java:185)
   at org.netbeans.api.java.source.JavaSourceTaskFactory$3.addPhaseCompletionTask(JavaSourceTaskFactory.java:234)
   at org.netbeans.api.java.source.JavaSourceTaskFactory.stateChangedImpl(JavaSourceTaskFactory.java:187)
   at org.netbeans.api.java.source.JavaSourceTaskFactory.access$000(JavaSourceTaskFactory.java:81)
   at org.netbeans.api.java.source.JavaSourceTaskFactory$1.run(JavaSourceTaskFactory.java:142)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.IllegalArgumentException: Task: org.netbeans.modules.java.editor.fold.JavaElementFoldManager$JavaElementFoldTask@b5b58a is already scheduled
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:425)
   at org.netbeans.api.java.source.JavaSourceTaskFactory.fileObjectsChanged(JavaSourceTaskFactory.java:140)
   at org.netbeans.api.java.source.support.EditorAwareJavaSourceTaskFactory.access$100(EditorAwareJavaSourceTaskFactory.java:60)
   at org.netbeans.api.java.source.support.EditorAwareJavaSourceTaskFactory$ChangeListenerImpl.stateChanged(EditorAwareJavaSourceTaskFactory.java:96)
   at org.netbeans.api.java.source.support.OpenedEditors.fireChangeEvent(OpenedEditors.java:119)
   at org.netbeans.api.java.source.support.OpenedEditors.stateChanged(OpenedEditors.java:175)
   at org.netbeans.api.java.source.support.OpenedEditors$1.propertyChange(OpenedEditors.java:89)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
   at org.netbeans.api.editor.EditorRegistry.fireEvents(EditorRegistry.java:514)
   at org.netbeans.api.editor.EditorRegistry.focusLost(EditorRegistry.java:348)
   at org.netbeans.api.editor.EditorRegistry$FocusL.focusLost(EditorRegistry.java:643)
   at java.awt.AWTEventMulticaster.focusLost(AWTEventMulticaster.java:213)
   at java.awt.AWTEventMulticaster.focusLost(AWTEventMulticaster.java:212)
   at java.awt.AWTEventMulticaster.focusLost(AWTEventMulticaster.java:212)
   at java.awt.Component.processFocusEvent(Component.java:6159)
   at java.awt.Component.processEvent(Component.java:6023)
   at java.awt.Container.processEvent(Container.java:2041)
   at java.awt.Component.dispatchEventImpl(Component.java:4630)
   at java.awt.Container.dispatchEventImpl(Container.java:2099)
   at java.awt.Component.dispatchEvent(Component.java:4460)
   at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1850)
   at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:910)
   at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:568)
   at java.awt.Component.dispatchEventImpl(Component.java:4502)
   at java.awt.Container.dispatchEventImpl(Container.java:2099)
   at java.awt.Component.dispatchEvent(Component.java:4460)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:148)
   at java.awt.SentEvent.dispatch(SentEvent.java:55)
   at java.awt.DefaultKeyboardFocusManager$DefaultKeyboardFocusManagerSentEvent.dispatch(DefaultKeyboardFocusManager.java:183)
   at java.awt.DefaultKeyboardFocusManager.sendMessage(DefaultKeyboardFocusManager.java:210)
   at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:635)
   at java.awt.Component.dispatchEventImpl(Component.java:4502)
   at java.awt.Container.dispatchEventImpl(Container.java:2099)
   at java.awt.Window.dispatchEventImpl(Window.java:2478)
   at java.awt.Component.dispatchEvent(Component.java:4460)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:148)
   at java.awt.SequencedEvent.dispatch(SequencedEvent.java:101)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:148)
   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)