java.lang.NullPointerException
   at com.sun.tools.javac.code.Types$DescriptorCache.findDescriptorInternal(Types.java:416)
   at com.sun.tools.javac.code.Types$DescriptorCache.get(Types.java:396)
   at com.sun.tools.javac.code.Types.findDescriptorSymbol(Types.java:564)
   at com.sun.tools.javac.comp.Check.checkFunctionalInterface(Check.java:3605)
   at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4405)
   at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4333)
   at com.sun.tools.javac.comp.Attr.attrib(Attr.java:4308)
   at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1314)
   at com.sun.tools.javac.api.JavacTaskImpl$1.process(JavacTaskImpl.java:473)
   at com.sun.tools.javac.api.JavacTaskImpl$Filter.run(JavacTaskImpl.java:623)
   at com.sun.tools.javac.api.JavacTaskImpl.analyze(JavacTaskImpl.java:476)
   at org.netbeans.modules.java.source.TreeLoader.loadTreeFor(TreeLoader.java:183)
   at com.sun.tools.javac.model.JavacElements.getTreeAndTopLevel(JavacElements.java:588)
   at com.sun.tools.javac.model.JavacElements.getTreeAndTopLevel(JavacElements.java:614)
   at com.sun.tools.javac.api.JavacTrees.getTree(JavacTrees.java:310)
   at com.sun.tools.javac.api.JavacTrees.getTree(JavacTrees.java:306)
   at com.sun.tools.javac.api.JavacTrees.getTree(JavacTrees.java:302)
   at com.sun.tools.javac.api.JavacTrees.getTree(JavacTrees.java:124)
   at org.netbeans.api.java.source.ui.ElementJavadoc.inheritedDocFor(ElementJavadoc.java:1450)
   at org.netbeans.api.java.source.ui.ElementJavadoc.prepareContent(ElementJavadoc.java:613)
   at org.netbeans.api.java.source.ui.ElementJavadoc.<init>(ElementJavadoc.java:381)
   at org.netbeans.api.java.source.ui.ElementJavadoc.create(ElementJavadoc.java:159)
   at org.netbeans.modules.editor.java.JavaCompletionDoc.create(JavaCompletionDoc.java:90)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.resolveDocumentation(JavaCompletionProvider.java:622)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.run(JavaCompletionProvider.java:454)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery$Task.run(JavaCompletionProvider.java:5883)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callUserTask(TaskProcessor.java:593)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:155)
   at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:139)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:206)
   at org.netbeans.modules.parsing.impl.TaskProcessor$2.call(TaskProcessor.java:203)
   at org.netbeans.modules.masterfs.filebasedfs.utils.FileChangedManager.priorityIO(FileChangedManager.java:176)
   at org.netbeans.modules.masterfs.providers.ProvidedExtensions.priorityIO(ProvidedExtensions.java:360)
   at org.netbeans.modules.parsing.impl.Utilities.runPriorityIO(Utilities.java:74)
Caused: org.netbeans.modules.parsing.spi.ParseException
   at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:211)
   at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:106)
   at org.netbeans.modules.editor.java.JavaCompletionProvider$JavaCompletionQuery.query(JavaCompletionProvider.java:320)
   at org.netbeans.spi.editor.completion.support.AsyncCompletionTask.run(AsyncCompletionTask.java:223)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1432)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2042)