java.lang.NullPointerException: The p parameter cannot be null
   at org.openide.util.Parameters.notNull(Parameters.java:89)
   at org.netbeans.spi.project.support.GenericSources.group(GenericSources.java:120)
   at org.netbeans.modules.scala.project.J2SESources$1.run(J2SESources.java:122)
   at org.netbeans.modules.scala.project.J2SESources$1.run(J2SESources.java:106)
   at org.openide.util.Mutex.readAccess(Mutex.java:288)
   at org.netbeans.modules.scala.project.J2SESources.getSourceGroups(J2SESources.java:106)
   at org.netbeans.spi.project.support.LookupProviderSupport$SourcesImpl.getSourceGroups(LookupProviderSupport.java:292)
   at org.netbeans.modules.parsing.impl.indexing.errors.TaskProvider.setScope(TaskProvider.java:147)
   at org.netbeans.modules.tasklist.impl.TaskManagerImpl.doRefresh(TaskManagerImpl.java:347)
   at org.netbeans.modules.tasklist.impl.TaskManagerImpl.access$200(TaskManagerImpl.java:76)
   at org.netbeans.modules.tasklist.impl.TaskManagerImpl$3.run(TaskManagerImpl.java:333)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1424)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1968)