java.lang.IllegalArgumentException: Root cannot be null.
   at org.netbeans.modules.java.classpath.SimplePathResourceImplementation.verify(SimplePathResourceImplementation.java:85)
   at org.netbeans.modules.java.classpath.SimplePathResourceImplementation.verify(SimplePathResourceImplementation.java:68)
   at org.netbeans.modules.java.classpath.SimplePathResourceImplementation.<init>(SimplePathResourceImplementation.java:126)
   at org.netbeans.spi.java.classpath.support.ClassPathSupport.createResource(ClassPathSupport.java:77)
   at org.netbeans.modules.maven.classpath.EndorsedClassPathImpl.getResources(EndorsedClassPathImpl.java:128)
   at org.netbeans.modules.maven.classpath.BootClassPathImpl.getResources(BootClassPathImpl.java:97)
   at org.netbeans.api.java.classpath.ClassPath.entries(ClassPath.java:350)
   at org.netbeans.api.java.classpath.ClassPath.getRoots(ClassPath.java:262)
   at org.netbeans.api.java.classpath.ClassPath.findResource(ClassPath.java:448)
   at org.netbeans.modules.java.source.parsing.JavacParser.validateSourceLevel(JavacParser.java:854)
   at org.netbeans.modules.java.source.parsing.JavacParser.createJavacTask(JavacParser.java:747)
   at org.netbeans.modules.java.source.parsing.JavacParser.createJavacTask(JavacParser.java:733)
   at org.netbeans.modules.java.source.parsing.CompilationInfoImpl.getJavacTask(CompilationInfoImpl.java:398)
   at org.netbeans.modules.java.source.parsing.JavacParser.getResult(JavacParser.java:511)
   at org.netbeans.modules.java.source.parsing.JavacParser.getResult(JavacParser.java:169)
   at org.netbeans.modules.parsing.impl.TaskProcessor.callGetResult(TaskProcessor.java:606)
   at org.netbeans.modules.parsing.impl.SourceCache.getResult(SourceCache.java:247)
   at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:718)
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
   at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
   at java.util.concurrent.FutureTask.run(FutureTask.java:166)
   at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
   at java.lang.Thread.run(Thread.java:722)