* VMixed (process): Do not use the target element itself as a

  relationship
* VDefault (isEmptySubject, isEmptyObjective): Check if the name is
  null.

Author: himi

org.omg.sysml.plantuml/src/org/omg/sysml/plantuml/VDefault.java

@@ -304,13 +304,15 @@ protected Relationship findBindingLikeRel(Feature f) {
 
     protected static boolean isEmptySubject(SubjectMembership sm) {
         Usage u = sm.getOwnedSubjectParameter();
-        if (!"subj".equals(u.getName())) return false;
+        String name = u.getName();
+        if (name != null && !"subj".equals(u.getName())) return false;
         return u.getOwnedRelationship().isEmpty();
     }
 
     protected static boolean isEmptyObjective(ObjectiveMembership om) {
         Usage u = om.getOwnedObjectiveRequirement();
-        if (!"obj".equals(u.getName())) return false;
+        String name = u.getName();
+        if (name != null && !"obj".equals(u.getName())) return false;
         return isEmpty(u);
     }
 

org.omg.sysml.plantuml/src/org/omg/sysml/plantuml/VMixed.java

@@ -57,7 +57,7 @@ protected VTree newVTree(Namespace namespace, Membership membership) {
 
     private String process(Visitor v, Element e) {
         v.visit(e);
-        addRel(e, e, null);
+        addRel(e, null);
         v.flush();
         return "";
     }
@@ -69,19 +69,13 @@ private String process(Visitor v, Element e) {
     @Override
     public String caseActionDefinition(ActionDefinition ad) {
         VAction va = new VAction(this);
-        va.caseActionDefinition(ad);
-        addRel(ad, null);
-        va.flush();
-        return "";
+        return process(va, ad);
     }
 
     @Override
     public String caseActionUsage(ActionUsage au) {
         VAction va = new VAction(this);
-        va.caseActionUsage(au);
-        addRel(au, null);
-        va.flush();
-        return "";
+        return process(va, au);
     }
 
     /***************************************************