The root Locality has an empty reference which prevents VisualLoclaity from referencing it. As a result, the following exception is thrown when deserialising a PolicyNet model:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at org.workcraft.util.Hierarchy.getTopParent(Hierarchy.java:87)
at org.workcraft.dom.AbstractGroup.isSameModel(AbstractGroup.java:162)
at org.workcraft.dom.AbstractGroup.reparent(AbstractGroup.java:149)
at org.workcraft.dom.math.MathGroup.reparent(MathGroup.java:92)
at org.workcraft.plugins.policy.VisualLocality.add(VisualLocality.java:29)
at org.workcraft.plugins.policy.VisualLocality.add(VisualLocality.java:42)
at org.workcraft.serialisation.xml.XMLDeserialisationManager.finaliseInstances(XMLDeserialisationManager.java:137)
at org.workcraft.plugins.serialisation.XMLModelDeserialiser.deserialise(XMLModelDeserialiser.java:68)
at org.workcraft.Framework.load(Framework.java:639)
at org.workcraft.Framework.loadFile(Framework.java:527)
at org.workcraft.workspace.Workspace.open(Workspace.java:109)
at org.workcraft.gui.MainWindow.openWork(MainWindow.java:837)
at org.workcraft.gui.MainWindow.openWork(MainWindow.java:826)
at org.workcraft.gui.MainWindowActions$2.run(MainWindowActions.java:23)
at org.workcraft.gui.MainWindow$1.actionPerformed(MainWindow.java:108)
at org.workcraft.gui.actions.ActionMenuItem.fireActionPerformed(ActionMenuItem.java:58)
at org.workcraft.gui.actions.ActionMenuItem.access$0(ActionMenuItem.java:55)
at org.workcraft.gui.actions.ActionMenuItem$ActionForwarder.actionPerformed(ActionMenuItem.java:34)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
at javax.swing.AbstractButton.doClick(AbstractButton.java:356)
at javax.swing.plaf.basic.BasicMenuItemUI$Actions.actionPerformed(BasicMenuItemUI.java:802)
at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1661)
at javax.swing.JComponent.processKeyBinding(JComponent.java:2870)
at javax.swing.JMenuBar.processBindingForKeyStrokeRecursive(JMenuBar.java:689)
at javax.swing.JMenuBar.processBindingForKeyStrokeRecursive(JMenuBar.java:697)
at javax.swing.JMenuBar.processBindingForKeyStrokeRecursive(JMenuBar.java:697)
at javax.swing.JMenuBar.processKeyBinding(JMenuBar.java:668)
at javax.swing.KeyboardManager.fireBinding(KeyboardManager.java:306)
at javax.swing.KeyboardManager.fireKeyboardAction(KeyboardManager.java:292)
at javax.swing.JComponent.processKeyBindingsForAllComponents(JComponent.java:2962)
at javax.swing.JComponent.processKeyBindings(JComponent.java:2954)
at javax.swing.JComponent.processKeyEvent(JComponent.java:2833)
at java.awt.Component.processEvent(Component.java:6282)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1895)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:762)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1027)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:899)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:727)
at java.awt.Component.dispatchEventImpl(Component.java:4731)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:729)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:688)
at java.awt.EventQueue$3.run(EventQueue.java:686)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:702)
at java.awt.EventQueue$4.run(EventQueue.java:700)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
Previously all MathGroups had references. Now the root MathGroup cannot be issued a reference as it does not have a parent (and therefore does not have a NamespaceProvider with NameManager). A solution is to give the root MathGroup some unique name, for example "/" that cannot be assigned by a user as it is not C-style.