java.lang.IllegalArgumentException: Comparison method violates its general contract!
   at java.util.ComparableTimSort.mergeLo(ComparableTimSort.java:714)
   at java.util.ComparableTimSort.mergeAt(ComparableTimSort.java:451)
   at java.util.ComparableTimSort.mergeCollapse(ComparableTimSort.java:374)
   at java.util.ComparableTimSort.sort(ComparableTimSort.java:182)
   at java.util.ComparableTimSort.sort(ComparableTimSort.java:146)
   at java.util.Arrays.sort(Arrays.java:472)
   at java.util.Collections.sort(Collections.java:155)
   at org.netbeans.modules.maven.indexer.NexusRepositoryIndexerImpl.find(NexusRepositoryIndexerImpl.java:1312)
   at org.netbeans.modules.maven.indexer.NexusRepositoryIndexerImpl.find(NexusRepositoryIndexerImpl.java:1249)
   at org.netbeans.modules.maven.indexer.api.RepositoryQueries.findResult(RepositoryQueries.java:487)
   at org.netbeans.modules.maven.nodes.AddDependencyPanel$QueryPanel$2.run(AddDependencyPanel.java:1128)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1454)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2036)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.IllegalArgumentException: Comparison method violates its general contract!
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:424)
   at org.netbeans.modules.maven.nodes.AddDependencyPanel$QueryPanel.find(AddDependencyPanel.java:1121)
   at org.netbeans.modules.maven.nodes.AddDependencyPanel$QueryPanel.stateChanged(AddDependencyPanel.java:1057)
   at org.netbeans.modules.maven.api.customizer.support.DelayedDocumentChangeListener$1.actionPerformed(DelayedDocumentChangeListener.java:76)
   at javax.swing.Timer.fireActionPerformed(Timer.java:312)
   at javax.swing.Timer$DoPostEvent.run(Timer.java:244)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:721)
   at java.awt.EventQueue.access$200(EventQueue.java:103)
   at java.awt.EventQueue$3.run(EventQueue.java:682)
   at java.awt.EventQueue$3.run(EventQueue.java:680)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:691)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:158)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:155)
   at java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:182)
   at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:221)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:219)
   at java.awt.Dialog.show(Dialog.java:1077)
   at org.netbeans.core.windows.services.NbPresenter.superShow(NbPresenter.java:1074)
   at org.netbeans.core.windows.services.NbPresenter.doShow(NbPresenter.java:1114)
   at org.netbeans.core.windows.services.NbPresenter.run(NbPresenter.java:1096)
   at org.netbeans.core.windows.services.NbPresenter.run(NbPresenter.java:126)
   at org.openide.util.Mutex.doEventAccess(Mutex.java:1363)
   at org.openide.util.Mutex.readAccess(Mutex.java:273)
   at org.netbeans.core.windows.services.NbPresenter.show(NbPresenter.java:1081)
   at java.awt.Component.show(Component.java:1651)
   at java.awt.Component.setVisible(Component.java:1603)
   at java.awt.Window.setVisible(Window.java:1014)
   at java.awt.Dialog.setVisible(Dialog.java:1003)
   at org.netbeans.core.NotifyExcPanel.updateState(NotifyExcPanel.java:397)
   at org.netbeans.core.NotifyExcPanel.access$400(NotifyExcPanel.java:97)
   at org.netbeans.core.NotifyExcPanel$2.run(NotifyExcPanel.java:328)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:721)
   at java.awt.EventQueue.access$200(EventQueue.java:103)
   at java.awt.EventQueue$3.run(EventQueue.java:682)
   at java.awt.EventQueue$3.run(EventQueue.java:680)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:691)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:158)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:155)
   at java.awt.WaitDispatchSupport$2.run(WaitDispatchSupport.java:182)
   at java.awt.WaitDispatchSupport$4.run(WaitDispatchSupport.java:221)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.awt.WaitDispatchSupport.enter(WaitDispatchSupport.java:219)
   at java.awt.Dialog.show(Dialog.java:1077)
   at org.netbeans.core.windows.services.NbPresenter.superShow(NbPresenter.java:1074)
   at org.netbeans.core.windows.services.NbPresenter.doShow(NbPresenter.java:1114)
   at org.netbeans.core.windows.services.NbPresenter.run(NbPresenter.java:1096)
   at org.netbeans.core.windows.services.NbPresenter.run(NbPresenter.java:126)
   at org.openide.util.Mutex.doEventAccess(Mutex.java:1363)
   at org.openide.util.Mutex.readAccess(Mutex.java:273)
   at org.netbeans.core.windows.services.NbPresenter.show(NbPresenter.java:1081)
   at java.awt.Component.show(Component.java:1651)
   at java.awt.Component.setVisible(Component.java:1603)
   at java.awt.Window.setVisible(Window.java:1014)
   at java.awt.Dialog.setVisible(Dialog.java:1003)
   at org.netbeans.core.windows.services.DialogDisplayerImpl$1AWTQuery.showDialog(DialogDisplayerImpl.java:260)
   at org.netbeans.core.windows.services.DialogDisplayerImpl.notify(DialogDisplayerImpl.java:276)
   at org.netbeans.core.windows.services.DialogDisplayerImpl.notify(DialogDisplayerImpl.java:167)
   at org.netbeans.modules.maven.nodes.AddDependencyPanel.show(AddDependencyPanel.java:149)
   at org.netbeans.modules.maven.nodes.DependenciesNode$AddDependencyAction.actionPerformed(DependenciesNode.java:297)
   at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
   at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
   at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
   at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
   at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
   at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
   at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
   at java.awt.Component.processMouseEvent(Component.java:6505)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
   at java.awt.Component.processEvent(Component.java:6270)
   at java.awt.Container.processEvent(Container.java:2229)
   at java.awt.Component.dispatchEventImpl(Component.java:4861)
   at java.awt.Container.dispatchEventImpl(Container.java:2287)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4832)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4492)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4422)
   at java.awt.Container.dispatchEventImpl(Container.java:2273)
   at java.awt.Window.dispatchEventImpl(Window.java:2719)
   at java.awt.Component.dispatchEvent(Component.java:4687)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:723)
   at java.awt.EventQueue.access$200(EventQueue.java:103)
   at java.awt.EventQueue$3.run(EventQueue.java:682)
   at java.awt.EventQueue$3.run(EventQueue.java:680)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
   at java.awt.EventQueue$4.run(EventQueue.java:696)
   at java.awt.EventQueue$4.run(EventQueue.java:694)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:693)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:158)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)