docs: public final void add(GroupAddress a, boolean isUpdating)
  	{
  		if (getMainAddress().equals(a))
  			throw new KNXIllegalArgumentException("address equals datapoint main address");
  		if (isUpdating) {
  			if (!updating.contains(a))
  				updating.add(a);
  		}
  		else {
  			if (!invalidating.contains(a))
  				invalidating.add(a);
  		}
  	}