code: public void addUpdatingAddress(final GroupAddress ga)
  	{
  		if (getMainAddress().equals(ga))
  			throw new KNXIllegalArgumentException(
  					"updating address " + ga + " equals main address of this datapoint '" + getName() + "'");
  		if (!updating.contains(ga))
  			updating.add(ga);
  	}
docs: Adds an updating group address to this datapoint to indicate that KNX messages with that destination address are
  allowed to update the associated datapoint state (i.e., the state value related to this datapoint). An address is
  added at most once.
  
  @param ga the KNX group address to add