java.lang.NullPointerException
   at org.netbeans.modules.refactoring.java.plugins.RenameTransformer.visitCompilationUnit(RenameTransformer.java:101)
   at org.netbeans.modules.refactoring.java.plugins.RenameTransformer.visitCompilationUnit(RenameTransformer.java:83)
   at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:483)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:67)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin$TransformTask.run(JavaRefactoringPlugin.java:367)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin$TransformTask.run(JavaRefactoringPlugin.java:337)
   at org.netbeans.api.java.source.JavaSource$1.run(JavaSource.java:665)
   at org.netbeans.modules.parsing.api.ParserManager$MultiUserTaskAction.run(ParserManager.java:189)
   at org.netbeans.modules.parsing.api.ParserManager$MultiUserTaskAction.run(ParserManager.java:162)
   at org.netbeans.modules.parsing.impl.TaskProcessor$1.call(TaskProcessor.java:200)
   at org.netbeans.modules.parsing.impl.TaskProcessor$1.call(TaskProcessor.java:197)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:160)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:227)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:66)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:197)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:108)
   at org.netbeans.api.java.source.JavaSource.runModificationTask(JavaSource.java:681)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin.processFiles(JavaRefactoringPlugin.java:248)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin.createAndAddElements(JavaRefactoringPlugin.java:258)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin.createAndAddElements(JavaRefactoringPlugin.java:274)
   at org.netbeans.modules.refactoring.java.plugins.RenameRefactoringPlugin.prepare(RenameRefactoringPlugin.java:440)
   at org.netbeans.modules.refactoring.api.AbstractRefactoring.pluginsPrepare2(AbstractRefactoring.java:422)
   at org.netbeans.modules.refactoring.api.AbstractRefactoring.pluginsPrepare(AbstractRefactoring.java:406)
   at org.netbeans.modules.refactoring.api.AbstractRefactoring.prepare(AbstractRefactoring.java:217)
   at org.netbeans.modules.refactoring.spi.impl.ParametersPanel$Prepare.run(ParametersPanel.java:807)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1957)