java.lang.NullPointerException: The treePath parameter cannot be null
   at org.openide.util.Parameters.notNull(Parameters.java:89)
   at org.netbeans.api.java.source.TreePathHandle.create(TreePathHandle.java:226)
   at org.netbeans.modules.java.hints.introduce.IntroduceHint.computeIntroduceMethod(IntroduceHint.java:663)
   at org.netbeans.modules.java.hints.introduce.IntroduceHint.computeError(IntroduceHint.java:539)
   at org.netbeans.modules.java.hints.introduce.IntroduceHint.run(IntroduceHint.java:354)
   at org.netbeans.modules.java.hints.introduce.IntroduceHint.run(IntroduceHint.java:152)
   at org.netbeans.modules.java.source.JavaSourceAccessor$CancelableTaskWrapper.run(JavaSourceAccessor.java:298)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callParserResultTask(TaskProcessor.java:558)
   at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:734)
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
   at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
   at java.util.concurrent.FutureTask.run(FutureTask.java:138)
   at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
   at java.lang.Thread.run(Thread.java:662)