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$JCCompilationUnit.accept(JCTree.java:490)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:67)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin$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:666)
   at org.netbeans.api.java.source.JavaSource$1.run(JavaSource.java:656)
   at org.netbeans.api.java.source.JavaSource$MultiTask.run(JavaSource.java:482)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:154)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:138)
   at org.netbeans.modules.parsing.impl.TaskProcessor$1.call(TaskProcessor.java:202)
   at org.netbeans.modules.parsing.impl.TaskProcessor$1.call(TaskProcessor.java:199)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:168)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:356)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:66)
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:199)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:106)
   at org.netbeans.api.java.source.JavaSource.runUserActionTaskImpl(JavaSource.java:432)
   at org.netbeans.api.java.source.JavaSource.runUserActionTask(JavaSource.java:403)
   at org.netbeans.api.java.source.JavaSource.runModificationTask(JavaSource.java:678)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin.processFiles(JavaRefactoringPlugin.java:248)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin.createAndAddElements(JavaRefactoringPlugin.java:258)
   at org.netbeans.modules.refactoring.java.spi.JavaRefactoringPlugin.createAndAddElements(JavaRefactoringPlugin.java:274)
   at org.netbeans.modules.refactoring.java.plugins.RenameRefactoringPlugin.prepare(RenameRefactoringPlugin.java:444)
   at org.netbeans.modules.refactoring.api.AbstractRefactoring.pluginsPrepare2(AbstractRefactoring.java:419)
   at org.netbeans.modules.refactoring.api.AbstractRefactoring.pluginsPrepare(AbstractRefactoring.java:403)
   at org.netbeans.modules.refactoring.api.AbstractRefactoring.prepare(AbstractRefactoring.java:218)
   at org.netbeans.modules.refactoring.spi.impl.ParametersPanel$Prepare.run(ParametersPanel.java:851)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)