java.lang.IllegalArgumentException: Task: org.netbeans.modules.java.editor.fold.JavaElementFoldManager$JavaElementFoldTask@9676c9 is already scheduled
   at org.netbeans.modules.java.source.JavaSourceAccessor.addPhaseCompletionTask(JavaSourceAccessor.java:186)
   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$Processor.run(RequestProcessor.java:1973)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.IllegalArgumentException: Task: org.netbeans.modules.java.editor.fold.JavaElementFoldManager$JavaElementFoldTask@9676c9 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$1.propertyChange(OpenedEditors.java:89)
   at java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:335)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:327)
   at org.netbeans.api.editor.EditorRegistry.fireEvents(EditorRegistry.java:538)
   at org.netbeans.api.editor.EditorRegistry.focusGained(EditorRegistry.java:344)
   at org.netbeans.api.editor.EditorRegistry$FocusL.focusGained(EditorRegistry.java:669)
   at java.awt.AWTEventMulticaster.focusGained(AWTEventMulticaster.java:220)
   at java.awt.Component.processFocusEvent(Component.java:6393)
   at java.awt.Component.processEvent(Component.java:6260)
   at java.awt.Container.processEvent(Container.java:2229)
   at java.awt.Component.dispatchEventImpl(Component.java:4860)
   at java.awt.Container.dispatchEventImpl(Container.java:2287)
   at java.awt.Component.dispatchEvent(Component.java:4686)
   at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1908)
   at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:928)
   at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:560)
   at java.awt.Component.dispatchEventImpl(Component.java:4730)
   at java.awt.Container.dispatchEventImpl(Container.java:2287)
   at java.awt.Component.dispatchEvent(Component.java:4686)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
   at java.awt.EventQueue.access$000(EventQueue.java:101)
   at java.awt.EventQueue$3.run(EventQueue.java:666)
   at java.awt.EventQueue$3.run(EventQueue.java:664)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
   at java.awt.EventQueue$4.run(EventQueue.java:680)
   at java.awt.EventQueue$4.run(EventQueue.java:678)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:153)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)