java.lang.NullPointerException
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2565)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2565)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2565)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2565)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2565)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2565)
   at com.sun.tools.javac.jvm.ClassReader.readEnclosingMethodAttr(ClassReader.java:1460)
   at com.sun.tools.javac.jvm.ClassReader$10.read(ClassReader.java:1180)
   at com.sun.tools.javac.jvm.ClassReader.readAttrs(ClassReader.java:1554)
   at com.sun.tools.javac.jvm.ClassReader.readClassAttrs(ClassReader.java:1568)
   at com.sun.tools.javac.jvm.ClassReader.readClass(ClassReader.java:2632)
   at com.sun.tools.javac.jvm.ClassReader.readClassBuffer(ClassReader.java:2726)
   at com.sun.tools.javac.jvm.ClassReader.readClassFile(ClassReader.java:2739)
   at com.sun.tools.javac.code.ClassFinder.fillIn(ClassFinder.java:367)
   at com.sun.tools.javac.code.ClassFinder.complete(ClassFinder.java:294)
   at com.sun.tools.javac.code.Symbol.complete(Symbol.java:636)
   at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:1327)
   at com.sun.tools.javac.code.Symbol$ClassSymbol.flags(Symbol.java:1252)
   at com.sun.tools.javac.code.Symbol$TypeSymbol.getEnclosedElements(Symbol.java:805)
   at org.netbeans.modules.java.editor.base.imports.UnusedImports$DetectorVisitor.visitImport(UnusedImports.java:273)
   at org.netbeans.modules.java.editor.base.imports.UnusedImports$DetectorVisitor.visitImport(UnusedImports.java:130)
   at com.sun.tools.javac.tree.JCTree$JCImport.accept(JCTree.java:662)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
   at com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:103)
   at org.netbeans.modules.java.editor.base.imports.UnusedImports$DetectorVisitor.visitCompilationUnit(UnusedImports.java:189)
   at org.netbeans.modules.java.editor.base.imports.UnusedImports$DetectorVisitor.visitCompilationUnit(UnusedImports.java:130)
   at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:593)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at org.netbeans.modules.java.editor.base.imports.UnusedImports.process(UnusedImports.java:108)
   at org.netbeans.modules.java.editor.base.semantic.SemanticHighlighterBase.process(SemanticHighlighterBase.java:305)
   at org.netbeans.modules.java.editor.semantic.SemanticHighlighter.process(SemanticHighlighter.java:76)
   at org.netbeans.modules.java.editor.base.semantic.SemanticHighlighterBase.run(SemanticHighlighterBase.java:162)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callParserResultTask(TaskProcessor.java:584)
   at org.netbeans.modules.parsing.impl.TaskProcessor$RequestPerformer.run(TaskProcessor.java:809)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:304)
   at org.netbeans.modules.parsing.impl.TaskProcessor$RequestPerformer.execute(TaskProcessor.java:725)
   at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:686)
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
   at java.util.concurrent.FutureTask.run(FutureTask.java:266)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)