java.lang.NullPointerException
   at org.netbeans.modules.refactoring.java.plugins.ExtractSuperclassRefactoringPlugin$CreateSuperclassElement.run(ExtractSuperclassRefactoringPlugin.java:491)
   at org.netbeans.modules.refactoring.java.plugins.ExtractSuperclassRefactoringPlugin$CreateSuperclassElement.run(ExtractSuperclassRefactoringPlugin.java:335)
   at org.netbeans.api.java.source.JavaSource$1.run(JavaSource.java:670)
   at org.netbeans.api.java.source.JavaSource$1.run(JavaSource.java:660)
   at org.netbeans.api.java.source.JavaSource$MultiTask.run(JavaSource.java:487)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask(TaskProcessor.java:583)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:150)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:134)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:200)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:197)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:168)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:72)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:197)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:102)
   at org.netbeans.api.java.source.JavaSource.runUserActionTaskImpl(JavaSource.java:437)
   at org.netbeans.api.java.source.JavaSource.runUserActionTask(JavaSource.java:408)
   at org.netbeans.api.java.source.JavaSource.runModificationTask(JavaSource.java:681)
   at org.netbeans.modules.refactoring.java.plugins.ExtractSuperclassRefactoringPlugin$CreateSuperclassElement.performChange(ExtractSuperclassRefactoringPlugin.java:372)
   at org.netbeans.modules.refactoring.api.RefactoringSession.doRefactoring(RefactoringSession.java:137)
   at org.netbeans.modules.refactoring.spi.impl.UndoManager$SessionUndoItem.redo(UndoManager.java:402)
   at org.netbeans.modules.refactoring.spi.impl.UndoManager$2.run(UndoManager.java:261)
   at org.netbeans.modules.refactoring.spi.impl.UndoManager.redo(UndoManager.java:290)
   at org.netbeans.modules.refactoring.spi.impl.UndoableWrapper$UndoableEditDelegate.redo(UndoableWrapper.java:143)
   at org.openide.text.WrapUndoEdit.redo(WrapUndoEdit.java:118)
   at org.openide.awt.UndoRedo$Manager.redoTo(UndoRedo.java:293)
   at org.openide.awt.UndoRedo$Manager.redo(UndoRedo.java:263)
   at org.openide.text.UndoRedoManager.access$101(UndoRedoManager.java:98)
   at org.openide.text.UndoRedoManager$DocLockedRun.run(UndoRedoManager.java:640)
   at org.netbeans.editor.GuardedDocument.runAtomic(GuardedDocument.java:317)
   at org.openide.text.UndoRedoManager$DocLockedRun.<init>(UndoRedoManager.java:618)
   at org.openide.text.UndoRedoManager$DocLockedRun.<init>(UndoRedoManager.java:610)
   at org.openide.text.UndoRedoManager$DocLockedRun.<init>(UndoRedoManager.java:606)
   at org.openide.text.UndoRedoManager.redo(UndoRedoManager.java:424)
   at org.netbeans.core.multiview.MultiViewPeer$DelegateUndoRedo.redo(MultiViewPeer.java:817)
   at org.openide.actions.UndoRedoAction.actionPerformed(UndoRedoAction.java:230)
   at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
   at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
   at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
   at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
   at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:290)
   at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
   at java.awt.Component.processMouseEvent(Component.java:6505)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
   at java.awt.Component.processEvent(Component.java:6270)
   at java.awt.Container.processEvent(Container.java:2229)
   at java.awt.Component.dispatchEventImpl(Component.java:4861)
   at java.awt.Container.dispatchEventImpl(Container.java:2287)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4832)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4492)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4422)
   at java.awt.Container.dispatchEventImpl(Container.java:2273)
   at java.awt.Window.dispatchEventImpl(Window.java:2713)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   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:158)
   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)