java.lang.IllegalStateException: Should not acquire Children.MUTEX while holding ProjectManager.mutex()
        at org.openide.nodes.Children$ProjectManagerDeadlockDetector.execute(Children.java:1808)
        at org.openide.util.Mutex.postRequest(Mutex.java:1245)
        at org.openide.util.Mutex.postRequest(Mutex.java:1209)
        at org.openide.util.Mutex.postWriteRequest(Mutex.java:582)
        at org.openide.nodes.Children$Keys.applyKeys(Children.java:1513)
        at org.openide.nodes.Children$Keys.setKeys(Children.java:1457)
        at org.netbeans.spi.java.project.support.ui.PackageViewChildren.refreshKeys(PackageViewChildren.java:244)
        at org.netbeans.spi.java.project.support.ui.PackageViewChildren.fileFolderCreated(PackageViewChildren.java:396)
Caused: java.lang.reflect.InvocationTargetException
        at sun.reflect.GeneratedMethodAccessor6.invoke(GeneratedMethodAccessor6.java:0)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:451)
Caused: java.lang.reflect.UndeclaredThrowableException
        at $Proxy1.fileFolderCreated(.java:0)
        at org.openide.filesystems.FCLSupport$DispatchEventWrapper.dispatchEventImpl(FCLSupport.java:133)
        at org.openide.filesystems.FCLSupport$DispatchEventWrapper.dispatchEvent(FCLSupport.java:122)
        at org.openide.filesystems.FCLSupport.dispatchEvent(FCLSupport.java:99)
        at org.openide.filesystems.FileObject$ED.dispatch(FileObject.java:1052)
        at org.openide.filesystems.EventControl.invokeDispatchers(EventControl.java:203)
        at org.openide.filesystems.EventControl.exitAtomicAction(EventControl.java:177)
        at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:122)
        at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:509)
        at org.netbeans.spi.project.support.ant.AntProjectHelper.runSaveAA(AntProjectHelper.java:317)
        at org.netbeans.spi.project.support.ant.AntProjectHelper.saveXml(AntProjectHelper.java:333)
        at org.netbeans.spi.project.support.ant.AntProjectHelper.save(AntProjectHelper.java:595)
        at org.netbeans.spi.project.support.ant.AntProjectHelper.access$100(AntProjectHelper.java:103)
        at org.netbeans.spi.project.support.ant.AntProjectHelper$1.save(AntProjectHelper.java:141)
        at org.netbeans.modules.project.ant.AntBasedProjectFactorySingleton.saveProject(AntBasedProjectFactorySingleton.java:346)
        at org.netbeans.api.project.ProjectManager$6.run(ProjectManager.java:643)
        at org.netbeans.api.project.ProjectManager$6.run(ProjectManager.java:632)
        at org.openide.util.Mutex.writeAccess(Mutex.java:433)
        at org.netbeans.api.project.ProjectManager.saveProject(ProjectManager.java:632)
        at org.netbeans.modules.project.ui.OpenProjectList.close(OpenProjectList.java:793)
        at org.netbeans.modules.project.ui.actions.CloseProject.actionPerformed(CloseProject.java:73)
        at org.netbeans.modules.project.ui.actions.LookupSensitiveAction.actionPerformed(LookupSensitiveAction.java:166)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1882)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2202)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
        at javax.swing.AbstractButton.doClick(AbstractButton.java:334)
        at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1051)
        at apple.laf.CUIAquaMenuItem.doClick(CUIAquaMenuItem.java:119)
        at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:1092)
        at java.awt.Component.processMouseEvent(Component.java:5602)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3135)
        at java.awt.Component.processEvent(Component.java:5367)
        at java.awt.Container.processEvent(Container.java:2010)
        at java.awt.Component.dispatchEventImpl(Component.java:4068)
        at java.awt.Container.dispatchEventImpl(Container.java:2068)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4256)
        at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:3936)
        at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:3866)
        at java.awt.Container.dispatchEventImpl(Container.java:2054)
        at java.awt.Window.dispatchEventImpl(Window.java:1801)
        at java.awt.Component.dispatchEvent(Component.java:3903)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:463)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:131)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:269)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:190)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:184)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:176)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)