docs: public void disconnect(Destination d) throws KNXLinkClosedException
  	{
  		if (detached)
  			throw new KNXIllegalStateException("TL detached");
  		if (d.getState() != Destination.DESTROYED
  			&& d.getState() != Destination.DISCONNECTED)
  			disconnectIndicate(getProxy(d), true);
  	}