protected void updateSimpleRefID(Notification notification) {
   for (StructValue structValue : getStructValue()) {
     for (SimpleRef ref : structValue.getSimpleRef()) {
       if (ref.getRefID() != null) {
         if (ref.getRefID().equals(notification.getOldStringValue())) {
           ref.setRefID(notification.getNewStringValue());
           break;
         }
       } else if (ref.getRefID() == null && notification.getOldStringValue() == null) {
         ref.setRefID(notification.getNewStringValue());
         break;
       }
     }
   }
 }
 protected void updateSimpleRefs(Notification notification) {
   Simple simple = (Simple) notification.getNewValue();
   if (simple != null) { // Add Simple Refs associated with new value
     for (StructValue structValue : getStructValue()) {
       SimpleRef ref = PrfFactory.eINSTANCE.createSimpleRef();
       ref.setRefID(simple.getId());
       ref.setValue(PropertiesUtil.getDefaultValue(simple));
       SimpleRef oldRef = null;
       for (SimpleRef sr : structValue.getSimpleRef()) {
         if (sr.getRefID() != null && sr.getRefID().equals(simple.getId())) {
           oldRef = sr;
           break;
         }
       }
       if (oldRef != null) {
         structValue.getSimpleRef().remove(oldRef);
       }
       int index = this.getStruct().getSimple().indexOf(simple);
       structValue.getSimpleRef().add(index, ref);
     }
   } else { // Remove SimpleRefs associated with the oldValue
     simple = (Simple) notification.getOldValue();
     if (simple != null) {
       for (StructValue structValue : getStructValue()) {
         Collection<SimpleRef> removeRefs = null;
         for (SimpleRef ref : structValue.getSimpleRef()) {
           if (ref.getRefID() != null && simple.getId() != null) {
             if (ref.getRefID().equals(simple.getId())) {
               removeRefs = Collections.singletonList(ref);
               break;
             }
           } else if (ref.getRefID() == null && simple.getId() == null) {
             removeRefs = Collections.singletonList(ref);
             break;
           }
         }
         if (removeRefs != null) {
           structValue.getSimpleRef().removeAll(removeRefs);
         }
       }
     }
   }
 }