java.lang.IllegalArgumentException: Duplicate in children list: /home/felipee/NetBeansProjects/refactoring/newFolder/keep
Children: [MasterFileObject[/home/felipee/NetBeansProjects/refactoring/newFolder/keep@484202d8:7a0b1959,valid=true], MasterFileObject[/home/felipee/NetBeansProjects/refactoring/newFolder/keep@484202d8:7a0b1959,valid=true]]
   at org.openide.filesystems.Ordering.getOrder(Ordering.java:98)
   at org.openide.filesystems.FileUtil.getOrder(FileUtil.java:2082)
   at org.openide.loaders.FolderChildren$1R.run(FolderChildren.java:157)
   at org.openide.loaders.FolderChildren.refreshChildren(FolderChildren.java:188)
   at org.openide.loaders.FolderChildren.addNotify(FolderChildren.java:291)
   at org.openide.nodes.Children.callAddNotify(Children.java:551)
   at org.openide.nodes.EntrySupport$Lazy.checkInit(EntrySupport.java:1030)
   at org.openide.nodes.EntrySupport$Lazy.getNodesCount(EntrySupport.java:1228)
   at org.openide.nodes.FilterNode$Children$LazySupport.updateEntries(FilterNode.java:1811)
   at org.openide.nodes.FilterNode$Children$LazySupport.update(FilterNode.java:1801)
   at org.openide.nodes.FilterNode$Children.addNotifyImpl(FilterNode.java:1479)
   at org.openide.nodes.FilterNode$Children.addNotify(FilterNode.java:1472)
   at org.openide.nodes.Children.callAddNotify(Children.java:551)
   at org.openide.nodes.EntrySupport$Lazy.checkInit(EntrySupport.java:1030)
   at org.openide.nodes.EntrySupport$Lazy.getNodesCount(EntrySupport.java:1228)
   at org.openide.nodes.FilterNode$Children$LazySupport.updateEntries(FilterNode.java:1811)
   at org.openide.nodes.FilterNode$Children$LazySupport.update(FilterNode.java:1801)
   at org.openide.nodes.FilterNode$Children.addNotifyImpl(FilterNode.java:1479)
   at org.openide.nodes.FilterNode$Children.addNotify(FilterNode.java:1472)
   at org.openide.nodes.Children.callAddNotify(Children.java:551)
   at org.openide.nodes.EntrySupport$Lazy.checkInit(EntrySupport.java:1030)
   at org.openide.nodes.EntrySupport$Lazy.getNodesCount(EntrySupport.java:1228)
   at org.openide.nodes.Children.getNodesCount(Children.java:485)
   at org.openide.explorer.view.VisualizerNode.getChildren(VisualizerNode.java:255)
   at org.openide.explorer.view.VisualizerNode.getChildren(VisualizerNode.java:245)
   at org.openide.explorer.view.VisualizerNode.getChildCount(VisualizerNode.java:322)
   at javax.swing.tree.DefaultTreeModel.getChildCount(DefaultTreeModel.java:168)
   at javax.swing.tree.FixedHeightLayoutCache$FHTreeStateNode.expand(FixedHeightLayoutCache.java:1135)
   at javax.swing.tree.FixedHeightLayoutCache.ensurePathIsExpanded(FixedHeightLayoutCache.java:645)
   at javax.swing.tree.FixedHeightLayoutCache.setExpandedState(FixedHeightLayoutCache.java:282)
   at javax.swing.plaf.basic.BasicTreeUI.updateExpandedDescendants(BasicTreeUI.java:1648)
   at javax.swing.plaf.basic.BasicTreeUI$Handler.treeExpanded(BasicTreeUI.java:3721)
   at javax.swing.JTree.fireTreeExpanded(JTree.java:2656)
   at javax.swing.JTree.setExpandedState(JTree.java:3427)
   at javax.swing.JTree.expandPath(JTree.java:2163)
   at javax.swing.plaf.basic.BasicTreeUI.toggleExpandState(BasicTreeUI.java:2209)
   at javax.swing.plaf.basic.BasicTreeUI.handleExpandControlClick(BasicTreeUI.java:2196)
   at javax.swing.plaf.basic.BasicTreeUI.checkForClickInExpandControl(BasicTreeUI.java:2154)
   at javax.swing.plaf.basic.BasicTreeUI$Handler.handleSelection(BasicTreeUI.java:3516)
   at javax.swing.plaf.basic.BasicTreeUI$Handler.mousePressedDND(BasicTreeUI.java:3502)
   at javax.swing.plaf.basic.BasicTreeUI$Handler.mousePressed(BasicTreeUI.java:3461)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:262)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:262)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:262)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:262)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:262)
   at java.awt.AWTEventMulticaster.mousePressed(AWTEventMulticaster.java:262)
   at java.awt.Component.processMouseEvent(Component.java:6260)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3267)
   at java.awt.Component.processEvent(Component.java:6028)
   at java.awt.Container.processEvent(Container.java:2041)
   at java.awt.Component.dispatchEventImpl(Component.java:4630)
   at java.awt.Container.dispatchEventImpl(Container.java:2099)
   at java.awt.Component.dispatchEvent(Component.java:4460)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4574)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4235)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4168)
   at java.awt.Container.dispatchEventImpl(Container.java:2085)
   at java.awt.Window.dispatchEventImpl(Window.java:2475)
   at java.awt.Component.dispatchEvent(Component.java:4460)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:134)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)