java.lang.IllegalStateException: Too many org.netbeans.modules.maven.nodes.SourcesNodeFactory$NList$1 (3) in shared RequestProcessor; create your own
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:419)
   at org.netbeans.modules.maven.nodes.SourcesNodeFactory$NList.stateChanged(SourcesNodeFactory.java:141)
   at org.openide.util.ChangeSupport.fireChange(ChangeSupport.java:130)
   at org.openide.util.ChangeSupport.fireChange(ChangeSupport.java:116)
   at org.netbeans.spi.project.support.LookupProviderSupport$SourcesImpl.setLookup(LookupProviderSupport.java:276)
   at org.netbeans.spi.project.support.LookupProviderSupport$SourcesImpl.access$300(LookupProviderSupport.java:251)
   at org.netbeans.spi.project.support.LookupProviderSupport$SourcesMerger.merge(LookupProviderSupport.java:246)
   at org.netbeans.spi.project.support.LookupProviderSupport$SourcesMerger.merge(LookupProviderSupport.java:235)
   at org.netbeans.spi.project.support.LookupProviderSupport$DelegatingLookupImpl.doDelegate(LookupProviderSupport.java:222)
   at org.netbeans.spi.project.support.LookupProviderSupport$DelegatingLookupImpl.resultChanged(LookupProviderSupport.java:160)
   at org.openide.util.lookup.ProxyLookup$1Notify.run(ProxyLookup.java:173)
   at org.openide.util.lookup.ProxyLookup.setLookups(ProxyLookup.java:179)
   at org.openide.util.lookup.ProxyLookup.setLookups(ProxyLookup.java:119)
   at org.netbeans.modules.projectapi.LazyLookupProviders$1$1.beforeLookup(LazyLookupProviders.java:85)
   at org.openide.util.lookup.ProxyLookup.lookup(ProxyLookup.java:197)
   at org.openide.util.lookup.ProxyLookup.lookup(ProxyLookup.java:205)
   at org.openide.util.lookup.ExcludingLookup.lookup(ExcludingLookup.java:105)
   at org.openide.util.lookup.ProxyLookup.lookup(ProxyLookup.java:205)
   at org.openide.util.lookup.ProxyLookup.lookup(ProxyLookup.java:205)
   at org.netbeans.modules.j2ee.persistenceapi.ProjectEntityClassScopeProvider.findEntityClassScope(ProjectEntityClassScopeProvider.java:60)
   at org.netbeans.modules.j2ee.persistence.api.EntityClassScope.getEntityClassScope(EntityClassScope.java:89)
   at org.netbeans.modules.j2ee.jpa.model.ModelUtils.getModel(ModelUtils.java:232)
   at org.netbeans.modules.j2ee.jpa.verification.JPAProblemFinder.run(JPAProblemFinder.java:125)
   at org.netbeans.modules.j2ee.jpa.verification.JPAProblemFinder$ProblemFinderCompInfo.run(JPAProblemFinder.java:384)
   at org.netbeans.modules.java.source.JavaSourceAccessor$CancelableTaskWrapper.run(JavaSourceAccessor.java:302)
   at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:657)
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
   at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
   at java.util.concurrent.FutureTask.run(FutureTask.java:138)
   at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
   at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
   at java.lang.Thread.run(Thread.java:619)