code: @Override
  	public Set<String> getContainedIds() {
  		Set<String> s = super.getContainedIds();
  		for (Constraint c : map.values()) {
  			s.addAll(c.getContainedIds());
  		}
  		return s;
  	}
docs: Returns the set union of all id set of the contained constraints plus its own.