java.lang.NullPointerException
   at com.sun.tools.javac.comp.Check.checkImportedPackagesObservable(Check.java:3677)
   at com.sun.tools.javac.comp.TypeEnter.finishImports(TypeEnter.java:235)
   at com.sun.tools.javac.comp.TypeEnter.complete(TypeEnter.java:220)
   at com.sun.tools.javac.code.Symbol.complete(Symbol.java:590)
   at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:1105)
   at com.sun.tools.javac.comp.Enter.complete(Enter.java:721)
   at com.sun.tools.javac.main.JavaCompiler.readSourceFile(JavaCompiler.java:795)
   at com.sun.tools.javac.main.JavaCompiler.readSourceFile(JavaCompiler.java:756)
   at com.sun.tools.javac.main.JavaCompiler.access$100(JavaCompiler.java:90)
   at com.sun.tools.javac.main.JavaCompiler$1.complete(JavaCompiler.java:324)
   at com.sun.tools.javac.code.ClassFinder.fillIn(ClassFinder.java:365)
   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$1.complete(ClassFinder.java:169)
   at com.sun.tools.javac.code.Symbol.complete(Symbol.java:590)
   at com.sun.tools.javac.code.Symbol$ClassSymbol.complete(Symbol.java:1105)
   at com.sun.tools.javac.code.Symbol$ClassSymbol.flags(Symbol.java:1030)
   at com.sun.tools.javac.code.Symbol$TypeSymbol.getEnclosedElements(Symbol.java:757)
   at org.netbeans.modules.java.hints.bugs.NPECheck$VisitorImpl.visitMethod(NPECheck.java:943)
   at org.netbeans.modules.java.hints.bugs.NPECheck$VisitorImpl.visitMethod(NPECheck.java:423)
   at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:874)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:72)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at org.netbeans.modules.java.hints.bugs.NPECheck$VisitorImpl.scan(NPECheck.java:502)
   at org.netbeans.modules.java.hints.bugs.NPECheck$VisitorImpl.scan(NPECheck.java:423)
   at com.sun.source.util.TreeScanner.scan(TreeScanner.java:106)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:103)
   at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:114)
   at com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:188)
   at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:782)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:72)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at org.netbeans.modules.java.hints.bugs.NPECheck$VisitorImpl.scan(NPECheck.java:502)
   at org.netbeans.modules.java.hints.bugs.NPECheck$VisitorImpl.scan(NPECheck.java:423)
   at com.sun.source.util.TreeScanner.scan(TreeScanner.java:106)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:103)
   at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:114)
   at com.sun.source.util.TreeScanner.visitCompilationUnit(TreeScanner.java:145)
   at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:563)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:72)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at org.netbeans.modules.java.hints.bugs.NPECheck$VisitorImpl.scan(NPECheck.java:502)
   at org.netbeans.modules.java.hints.bugs.NPECheck.computeExpressionsState(NPECheck.java:381)
   at org.netbeans.modules.java.hints.bugs.NPECheck.methodInvocation(NPECheck.java:196)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(NativeMethodAccessorImpl.java:0)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:497)
   at org.netbeans.modules.java.hints.providers.code.CodeHintProviderImpl$WorkerImpl.createErrors(CodeHintProviderImpl.java:339)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker.runHint(HintsInvoker.java:810)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker.access$400(HintsInvoker.java:112)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.runAndAdd(HintsInvoker.java:669)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:688)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:622)
   at com.sun.source.util.TreeScanner.visitExpressionStatement(TreeScanner.java:434)
   at com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1430)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:72)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:694)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:622)
   at com.sun.source.util.TreeScanner.scan(TreeScanner.java:106)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:103)
   at com.sun.source.util.TreeScanner.visitBlock(TreeScanner.java:249)
   at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1002)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:72)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:694)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:622)
   at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:91)
   at com.sun.source.util.TreeScanner.visitMethod(TreeScanner.java:207)
   at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:874)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:72)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:694)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:622)
   at com.sun.source.util.TreeScanner.scan(TreeScanner.java:106)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:103)
   at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:114)
   at com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:188)
   at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:782)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:72)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:94)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:694)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:622)
   at com.sun.source.util.TreeScanner.scan(TreeScanner.java:106)
   at org.netbeans.api.java.source.support.CancellableTreePathScanner.scan(CancellableTreePathScanner.java:103)
   at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:114)
   at com.sun.source.util.TreeScanner.visitCompilationUnit(TreeScanner.java:145)
   at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:563)
   at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:53)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker$ScannerImpl.scan(HintsInvoker.java:713)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker.computeHintsImpl(HintsInvoker.java:257)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker.computeHints(HintsInvoker.java:240)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker.computeHints(HintsInvoker.java:210)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker.computeHints(HintsInvoker.java:183)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsInvoker.computeHints(HintsInvoker.java:150)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsTask.run(HintsTask.java:137)
   at org.netbeans.modules.java.hints.spiimpl.hints.HintsTask.run(HintsTask.java:88)
   at org.netbeans.modules.java.source.JavaSourceAccessor$CancelableTaskWrapper.run(JavaSourceAccessor.java:298)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callParserResultTask(TaskProcessor.java:584)
   at org.netbeans.modules.parsing.impl.TaskProcessor$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)