org.dom4j.DocumentException: unknown protocol: c Nested exception: unknown protocol: c
   at org.dom4j.io.SAXReader.read(SAXReader.java:484)
   at org.dom4j.io.SAXReader.read(SAXReader.java:321)
   at org.uml.filetype.cdg.ClassDiagramDataObject.readFromFile(ClassDiagramDataObject.java:207)
   at org.uml.filetype.cdg.ClassDiagramDataObject.open(ClassDiagramDataObject.java:167)
   at org.openide.awt.ActionDefaultPerfomer.actionPerformed(ActionDefaultPerfomer.java:70)
   at org.openide.awt.ContextAction$Performer.actionPerformed(ContextAction.java:226)
   at org.openide.awt.ContextManager.actionPerformed(ContextManager.java:260)
   at org.openide.awt.ContextAction.actionPerformed(ContextAction.java:109)
   at org.openide.util.actions.ActionInvoker$1.run(ActionInvoker.java:93)
   at org.openide.util.actions.ActionInvoker.doPerformAction(ActionInvoker.java:116)
   at org.openide.util.actions.ActionInvoker.invokeAction(ActionInvoker.java:99)
   at org.openide.awt.GeneralAction$BaseDelAction.actionPerformed(GeneralAction.java:234)
   at org.openide.explorer.view.TreeView$PopupSupport.mouseClicked(TreeView.java:1625)
   at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:270)
   at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:269)
   at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:269)
   at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:269)
   at java.awt.Component.processMouseEvent(Component.java:6528)
   at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
   at java.awt.Component.processEvent(Component.java:6290)
   at java.awt.Container.processEvent(Container.java:2234)
   at java.awt.Component.dispatchEventImpl(Component.java:4881)
   at java.awt.Container.dispatchEventImpl(Container.java:2292)
   at java.awt.Component.dispatchEvent(Component.java:4703)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4898)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4542)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4462)
   at java.awt.Container.dispatchEventImpl(Container.java:2278)
   at java.awt.Window.dispatchEventImpl(Window.java:2739)
   at java.awt.Component.dispatchEvent(Component.java:4703)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:746)
   at java.awt.EventQueue.access$400(EventQueue.java:97)
   at java.awt.EventQueue$3.run(EventQueue.java:697)
   at java.awt.EventQueue$3.run(EventQueue.java:691)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:86)
   at java.awt.EventQueue$4.run(EventQueue.java:719)
   at java.awt.EventQueue$4.run(EventQueue.java:717)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:75)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:716)
   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)