code: protected EClass getAssociatedClusterType(EClass eClass) {
  		if (clusterTypes.contains(eClass))
  			return eClass;
  		EList<EClass> superTypes = eClass.getESuperTypes();
  		if (superTypes.isEmpty())
  			return eClass;
  		return getAssociatedClusterType(superTypes.get(0));
  	}
docs: Return the type that describes the set of instances that should have unique names.
  The default information will return the topmost type or the first super type that is contained
  in the set of cluster types ({@link NamesAreUniqueValidationHelper#getClusterTypes()}).
  Only the first super type will be taken into account when walking the hierarchy.