Removing the REST MED from a model causes the following exception:

Exception in thread "ModelBuffer.Save" java.lang.NullPointerException
at org.eclipse.emf.ecore.xmi.impl.XMLHelperImpl.getURIFragment(XMLHelperImpl.java:719)
at org.eclipse.emf.ecore.xmi.impl.XMLHelperImpl.getIDREF(XMLHelperImpl.java:753)
at org.eclipse.emf.ecore.xmi.impl.XMLSaveImpl.saveIDRefSingle(XMLSaveImpl.java:1972)
at com.metamatrix.modeler.internal.core.resource.xmi.MtkXmiSaveImpl.saveIDRefSingle(MtkXmiSaveImpl.java:298)
at org.eclipse.emf.ecore.xmi.impl.XMLSaveImpl.saveFeatures(XMLSaveImpl.java:1318)
at com.metamatrix.modeler.internal.core.resource.xmi.MtkXmiSaveImpl.saveElementID(MtkXmiSaveImpl.java:248)
at org.eclipse.emf.ecore.xmi.impl.XMLSaveImpl.saveElement(XMLSaveImpl.java:1174)
at org.eclipse.emf.ecore.xmi.impl.XMLSaveImpl.saveElement(XMLSaveImpl.java:1035)
at org.eclipse.emf.ecore.xmi.impl.XMLSaveImpl.saveContainedMany(XMLSaveImpl.java:2386)
at org.eclipse.emf.ecore.xmi.impl.XMLSaveImpl.saveFeatures(XMLSaveImpl.java:1533)
at com.metamatrix.modeler.internal.core.resource.xmi.MtkXmiSaveImpl.saveElementID(MtkXmiSaveImpl.java:248)
at org.eclipse.emf.ecore.xmi.impl.XMISaveImpl.writeTopObjects(XMISaveImpl.java:90)
at org.eclipse.emf.ecore.xmi.impl.XMLSaveImpl.traverse(XMLSaveImpl.java:592)
at org.eclipse.emf.ecore.xmi.impl.XMLSaveImpl.save(XMLSaveImpl.java:256)
at org.eclipse.emf.ecore.xmi.impl.XMLResourceImpl.doSave(XMLResourceImpl.java:206)
at com.metamatrix.modeler.internal.core.resource.xmi.MtkXmiResourceImpl.doSave(MtkXmiResourceImpl.java:354)
at org.eclipse.emf.ecore.resource.impl.ResourceImpl.save(ResourceImpl.java:1406)
at com.metamatrix.modeler.internal.core.workspace.ModelBufferImpl.saveInTransaction(ModelBufferImpl.java:559)
at com.metamatrix.modeler.internal.core.workspace.ModelBufferImpl$1.run(ModelBufferImpl.java:488)