code: private static Collection<? extends KNXAddress> ensureDeviceAck(final KNXMediumSettings settings,
  		final Collection<? extends KNXAddress> acknowledge)
  	{
  		if (settings.getMedium() != KNXMediumSettings.MEDIUM_TP1)
  			throw new KNXIllegalArgumentException("TP-UART link supports only TP1 medium");
  		// see if we have a valid device address assigned
  		final IndividualAddress device = settings.getDeviceAddress();
  		if (device.getDevice() == 0 || device.getDevice() == 0xff)
  			return acknowledge;
  
  		final ArrayList<KNXAddress> l = new ArrayList<>(acknowledge);
  		l.add(device);
  		return l;
  	}
docs: if possible, add this link to the list of addresses to acknowledge