java.lang.NullPointerException
   at org.netbeans.modules.java.freeform.Classpaths.createExecuteClasspath(Classpaths.java:484)
   at org.netbeans.modules.java.freeform.Classpaths.access$500(Classpaths.java:126)
   at org.netbeans.modules.java.freeform.Classpaths$MutableClassPathImplementation.initRoots(Classpaths.java:608)
   at org.netbeans.modules.java.freeform.Classpaths$MutableClassPathImplementation.change(Classpaths.java:649)
   at org.netbeans.modules.java.freeform.Classpaths.pathsChanged(Classpaths.java:554)
   at org.netbeans.modules.java.freeform.Classpaths.configurationXmlChanged(Classpaths.java:538)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$3.run(AntProjectHelper.java:524)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$3.run(AntProjectHelper.java:519)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.readAccess(DefaultMutexImplementation.java:252)
   at org.openide.util.Mutex.readAccess(Mutex.java:218)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.fireChange(AntProjectHelper.java:519)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.modifying(AntProjectHelper.java:545)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.access$900(AntProjectHelper.java:114)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$10.run(AntProjectHelper.java:987)
   at org.netbeans.spi.project.support.ant.AntProjectHelper$10.run(AntProjectHelper.java:960)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.writeAccess(DefaultMutexImplementation.java:293)
   at org.openide.util.Mutex.writeAccess(Mutex.java:271)
   at org.netbeans.spi.project.support.ant.AntProjectHelper.putConfigurationFragment(AntProjectHelper.java:960)
   at org.netbeans.spi.project.support.ant.ExtensibleMetadataProviderImpl.putConfigurationFragment(ExtensibleMetadataProviderImpl.java:90)
   at org.netbeans.modules.java.freeform.JavaProjectGenerator.putJavaCompilationUnits(JavaProjectGenerator.java:600)
   at org.netbeans.modules.java.freeform.ui.ProjectModel$2.run(ProjectModel.java:219)
   at org.netbeans.modules.java.freeform.ui.ProjectModel$2.run(ProjectModel.java:207)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.writeAccess(DefaultMutexImplementation.java:293)
   at org.openide.util.Mutex.writeAccess(Mutex.java:271)
   at org.netbeans.modules.java.freeform.ui.ProjectModel.saveProject(ProjectModel.java:207)
   at org.netbeans.modules.java.freeform.ui.SourceFoldersCategoryProvider$1.actionPerformed(SourceFoldersCategoryProvider.java:87)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.actionPerformed(CustomizerDialog.java:345)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.access$200(CustomizerDialog.java:253)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener$1.run(CustomizerDialog.java:279)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.writeAccess(DefaultMutexImplementation.java:293)
   at org.openide.util.Mutex.writeAccess(Mutex.java:271)
   at org.netbeans.modules.project.uiapi.CustomizerDialog$OptionListener.actionPerformed(CustomizerDialog.java:276)
   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:6535)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
   at java.awt.Component.processEvent(Component.java:6300)
   at java.awt.Container.processEvent(Container.java:2236)
   at java.awt.Component.dispatchEventImpl(Component.java:4891)
   at java.awt.Container.dispatchEventImpl(Container.java:2294)
   at java.awt.Component.dispatchEvent(Component.java:4713)
   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:2750)
   at java.awt.Component.dispatchEvent(Component.java:4713)
   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:76)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
   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:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
   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)