java.lang.NullPointerException
        at org.netbeans.modules.java.classpath.ContainerPathContent.add(ContainerPathContent.java:265)
        at org.netbeans.modules.java.classpath.PathContentCustomizer.addResources(PathContentCustomizer.java:280)
        at org.netbeans.modules.java.classpath.PathContentCustomizer.actionPerformed(PathContentCustomizer.java:348)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1786)
        at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1839)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:419)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:257)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:245)
        at java.awt.Component.processMouseEvent(Component.java:5103)
        at java.awt.Component.processEvent(Component.java:4900)
        at java.awt.Container.processEvent(Container.java:1569)
        at java.awt.Component.dispatchEventImpl(Component.java:3618)
        at java.awt.Container.dispatchEventImpl(Container.java:1627)
        at java.awt.Component.dispatchEvent(Component.java:3480)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3480)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3195)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3125)
        at java.awt.Container.dispatchEventImpl(Container.java:1613)
        at java.awt.Window.dispatchEventImpl(Window.java:1599)
        at java.awt.Component.dispatchEvent(Component.java:3480)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:451)
[catch] at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:141)
        at java.awt.Dialog$1.run(Dialog.java:539)
        at java.awt.Dialog.show(Dialog.java:560)
        at org.netbeans.core.NbPresenter.superShow(NbPresenter.java:687)
        at org.netbeans.core.NbPresenter.run(NbPresenter.java:720)
        at org.openide.util.Mutex.doEventAccess(Mutex.java:917)
        at org.openide.util.Mutex.readAccess(Mutex.java:161)
        at org.netbeans.core.NbPresenter.show(NbPresenter.java:701)
        at java.awt.Component.show(Component.java:1134)
        at java.awt.Component.setVisible(Component.java:1089)
        at org.netbeans.core.NbTopManager$2.run(NbTopManager.java:440)
        at org.openide.util.Mutex$1.run(Mutex.java:931)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:171)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:449)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)