java.lang.NullPointerException
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2376)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2387)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2384)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2385)
   at com.sun.tools.javac.jvm.ClassReader.enterTypevars(ClassReader.java:2385)
   at com.sun.tools.javac.jvm.ClassReader.readEnclosingMethodAttr(ClassReader.java:1344)
   at com.sun.tools.javac.jvm.ClassReader$10.read(ClassReader.java:1100)
   at com.sun.tools.javac.jvm.ClassReader.readAttrs(ClassReader.java:1438)
   at com.sun.tools.javac.jvm.ClassReader.readClassAttrs(ClassReader.java:1452)
   at com.sun.tools.javac.jvm.ClassReader.readClass(ClassReader.java:2449)
   at com.sun.tools.javac.jvm.ClassReader.readClassBuffer(ClassReader.java:2543)
   at com.sun.tools.javac.jvm.ClassReader.readClassFile(ClassReader.java:2556)
   at com.sun.tools.javac.code.ClassFinder.fillIn(ClassFinder.java:360)
   at com.sun.tools.javac.code.ClassFinder.complete(ClassFinder.java:293)
   at com.sun.tools.javac.code.ClassFinder.access$000(ClassFinder.java:75)
   at com.sun.tools.javac.code.ClassFinder$1.complete(ClassFinder.java:169)
   at com.sun.tools.javac.code.Symbol.complete(Symbol.java:630)
   at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:1262)
   at com.sun.tools.javac.code.Symbol$ClassSymbol.flags(Symbol.java:1187)
   at com.sun.tools.javac.code.Symbol$TypeSymbol.getEnclosedElements(Symbol.java:797)
   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$JCImport.accept(JCTree.java:648)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
   at com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:103)
   at org.netbeans.modules.java.editor.base.imports.UnusedImports$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:579)
   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:300)
   at org.netbeans.modules.java.editor.semantic.SemanticHighlighter.process(SemanticHighlighter.java:76)
   at org.netbeans.modules.java.editor.base.semantic.SemanticHighlighterBase.run(SemanticHighlighterBase.java:157)
   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)