java.lang.IllegalStateException: Too many org.netbeans.modules.maven.nodes.SourcesNodeFactory$NList$1 (2) in shared RequestProcessor; create your own
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:416)
   at org.netbeans.modules.maven.nodes.SourcesNodeFactory$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$SourcesImpl.setLookup(LookupProviderSupport.java:278)
   at org.netbeans.spi.project.support.LookupProviderSupport$SourcesImpl.access$200(LookupProviderSupport.java:253)
   at org.netbeans.spi.project.support.LookupProviderSupport$SourcesMerger.merge(LookupProviderSupport.java:248)
   at org.netbeans.spi.project.support.LookupProviderSupport$SourcesMerger.merge(LookupProviderSupport.java:237)
   at org.netbeans.spi.project.support.LookupProviderSupport$DelegatingLookupImpl.doDelegate(LookupProviderSupport.java:223)
   at org.netbeans.spi.project.support.LookupProviderSupport$DelegatingLookupImpl.resultChanged(LookupProviderSupport.java:157)
   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$1.beforeLookup(LazyLookupProviders.java:85)
   at org.openide.util.lookup.ProxyLookup$R.myBeforeLookup(ProxyLookup.java:655)
   at org.openide.util.lookup.ProxyLookup$R.beforeLookup(ProxyLookup.java:674)
   at org.openide.util.lookup.ProxyLookup$R.myBeforeLookup(ProxyLookup.java:663)
   at org.openide.util.lookup.ProxyLookup$R.computeResult(ProxyLookup.java:517)
   at org.openide.util.lookup.ProxyLookup$R.allInstances(ProxyLookup.java:488)
   at org.netbeans.modules.maven.MavenProjectPropsImpl$MergedAuxProperties.listKeys(MavenProjectPropsImpl.java:294)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences.getChildrenNames(AuxiliaryConfigBasedPreferencesProvider.java:584)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences.childSpi(AuxiliaryConfigBasedPreferencesProvider.java:538)
   at java.util.prefs.AbstractPreferences.node(AbstractPreferences.java:816)
   at java.util.prefs.AbstractPreferences.node(AbstractPreferences.java:796)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences.access$2101(AuxiliaryConfigBasedPreferencesProvider.java:425)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences$7.run(AuxiliaryConfigBasedPreferencesProvider.java:713)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences$7.run(AuxiliaryConfigBasedPreferencesProvider.java:711)
   at org.openide.util.Mutex.readAccess(Mutex.java:285)
   at org.netbeans.modules.projectapi.AuxiliaryConfigBasedPreferencesProvider$AuxiliaryConfigBasedPreferences.node(AuxiliaryConfigBasedPreferencesProvider.java:711)
   at org.netbeans.modules.editor.indent.project.ProjectAwareCodeStylePreferences$Csp$2.run(ProjectAwareCodeStylePreferences.java:194)
   at org.openide.util.Mutex.postRequest(Mutex.java:1251)
   at org.openide.util.Mutex.postReadRequest(Mutex.java:565)
   at org.netbeans.modules.editor.indent.project.ProjectAwareCodeStylePreferences$Csp.<init>(ProjectAwareCodeStylePreferences.java:189)
   at org.netbeans.modules.editor.indent.project.ProjectAwareCodeStylePreferences$1.getCsp(ProjectAwareCodeStylePreferences.java:123)
   at org.netbeans.modules.editor.indent.project.ProjectAwareCodeStylePreferences$1.forDocument(ProjectAwareCodeStylePreferences.java:98)
   at org.netbeans.modules.editor.indent.project.ProjectAwareCodeStylePreferences.forDocument(ProjectAwareCodeStylePreferences.java:81)
   at org.netbeans.modules.editor.indent.spi.CodeStylePreferences.getPreferences(CodeStylePreferences.java:161)
   at org.netbeans.modules.editor.indent.api.IndentUtils.indentLevelSize(IndentUtils.java:91)
   at org.netbeans.modules.editor.NbEditorDocument$4.put(NbEditorDocument.java:306)
   at javax.swing.text.AbstractDocument.putProperty(AbstractDocument.java:529)
   at org.openide.text.DataEditorSupport.createStyledDocument(DataEditorSupport.java:376)
   at org.openide.text.CloneableEditorSupport.prepareDocument(CloneableEditorSupport.java:633)
   at org.openide.text.CloneableEditorSupport.prepareDocument(CloneableEditorSupport.java:576)
   at org.openide.text.CloneableEditor$DoInitialize.initNonVisual(CloneableEditor.java:381)
   at org.openide.text.CloneableEditor$DoInitialize.run(CloneableEditor.java:324)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1417)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1955)