java.lang.AssertionError
   at org.netbeans.spi.project.support.ant.AntProjectHelper.save(AntProjectHelper.java:601)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.access$100(AntProjectHelper.java:89)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$1.save(AntProjectHelper.java:127)
   at org.netbeans.modules.project.ant.AntBasedProjectFactorySingleton.saveProject(AntBasedProjectFactorySingleton.java:406)
   at org.netbeans.modules.projectapi.nb.NbProjectManager$6.run(NbProjectManager.java:618)
   at org.netbeans.modules.projectapi.nb.NbProjectManager$6.run(NbProjectManager.java:608)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.writeAccess(DefaultMutexImplementation.java:229)
   at org.openide.util.Mutex.writeAccess(Mutex.java:274)
   at org.netbeans.modules.projectapi.nb.NbProjectManager.saveProject(NbProjectManager.java:608)
   at org.netbeans.api.project.ProjectManager.saveProject(ProjectManager.java:265)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.saveModifiedProject(CustomizerDialog.java:345)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.access$500(CustomizerDialog.java:228)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener$2$1$1.run(CustomizerDialog.java:293)
   at org.openide.filesystems.FileUtil$2.run(FileUtil.java:412)
   at org.openide.filesystems.EventControl.runAtomicAction(EventControl.java:102)
   at org.openide.filesystems.FileSystem.runAtomicAction(FileSystem.java:494)
   at org.openide.filesystems.FileUtil.runAtomicAction(FileUtil.java:396)
   at org.openide.filesystems.FileUtil.runAtomicAction(FileUtil.java:416)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener$2$1.run(CustomizerDialog.java:284)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.writeAccess(DefaultMutexImplementation.java:229)
   at org.openide.util.Mutex.writeAccess(Mutex.java:246)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener$2.run(CustomizerDialog.java:281)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:45)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:278)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2033)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.AssertionError
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:395)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.actionPerformed(CustomizerDialog.java:277)
   at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
   at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
   at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
   at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
   at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
   at java.awt.Component.processMouseEvent(Component.java:6533)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
   at java.awt.Component.processEvent(Component.java:6298)
   at java.awt.Container.processEvent(Container.java:2236)
   at java.awt.Component.dispatchEventImpl(Component.java:4889)
   at java.awt.Container.dispatchEventImpl(Container.java:2294)
   at java.awt.Component.dispatchEvent(Component.java:4711)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4888)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4525)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4466)
   at java.awt.Container.dispatchEventImpl(Container.java:2280)
   at java.awt.Window.dispatchEventImpl(Window.java:2746)
   at java.awt.Component.dispatchEvent(Component.java:4711)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
   at java.awt.EventQueue.access$500(EventQueue.java:97)
   at java.awt.EventQueue$3.run(EventQueue.java:709)
   at java.awt.EventQueue$3.run(EventQueue.java:703)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
   at java.awt.EventQueue$4.run(EventQueue.java:731)
   at java.awt.EventQueue$4.run(EventQueue.java:729)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:136)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)