docs: public void setKNXMedium(KNXMediumSettings settings)
  	{
  		if (settings == null)
  			throw new KNXIllegalArgumentException("medium settings are mandatory");
  		if (medium != null && !settings.getClass().isAssignableFrom(medium.getClass())
  			&& !medium.getClass().isAssignableFrom(settings.getClass()))
  			throw new KNXIllegalArgumentException("medium differs");
  		medium = settings;
  	}