java.lang.NullPointerException
        at com.sun.tools.javac.tree.TreeInfo$1DeclScanner.visitTypeParameter(TreeInfo.java:502)
        at com.sun.tools.javac.tree.JCTree$JCTypeParameter.accept(JCTree.java:1875)
        at com.sun.tools.javac.tree.TreeInfo$1DeclScanner.scan(TreeInfo.java:483)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:58)
        at com.sun.tools.javac.tree.TreeScanner.visitMethodDef(TreeScanner.java:87)
        at com.sun.tools.javac.tree.TreeInfo$1DeclScanner.visitMethodDef(TreeInfo.java:495)
        at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:658)
        at com.sun.tools.javac.tree.TreeInfo$1DeclScanner.scan(TreeInfo.java:483)
        at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:58)
        at com.sun.tools.javac.tree.TreeScanner.visitClassDef(TreeScanner.java:81)
        at com.sun.tools.javac.tree.TreeInfo$1DeclScanner.visitClassDef(TreeInfo.java:491)
        at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:590)
        at com.sun.tools.javac.tree.TreeInfo.declarationFor(TreeInfo.java:507)
        at com.sun.tools.javac.model.JavacElements.getTreeAndTopLevel(JavacElements.java:633)
        at com.sun.tools.javac.model.JavacElements.getTreeAndTopLevel(JavacElements.java:653)
        at com.sun.tools.javac.api.JavacTrees.getPath(JavacTrees.java:170)
        at com.sun.tools.javac.api.JavacTrees.getPath(JavacTrees.java:162)
        at org.netbeans.api.java.source.TreePathHandle.create(TreePathHandle.java:313)
        at org.netbeans.modules.java.navigation.ElementScanningTask.element2description(ElementScanningTask.java:225)
        at org.netbeans.modules.java.navigation.ElementScanningTask.addMembers(ElementScanningTask.java:210)
        at org.netbeans.modules.java.navigation.ElementScanningTask.run(ElementScanningTask.java:129)
        at org.netbeans.modules.java.navigation.ElementScanningTask.run(ElementScanningTask.java:86)
        at org.netbeans.api.java.source.JavaSource$CompilationJob.run(JavaSource.java:1558)
        at java.util.concurrent.Executors$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:885)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
        at java.lang.Thread.run(Thread.java:619)