code: @Override
      int write_attribute_asynch_i(final DeviceAttribute da, final boolean fwd, final int rid) throws DevFailed {
  	synchronized (this) {
  	    final Iterator it = elements.iterator();
  	    while (it.hasNext()) {
  		final GroupElement e = (GroupElement) it.next();
  		if (e instanceof GroupDeviceElement || fwd) {
  		    e.write_attribute_asynch_i(da, fwd, rid);
  		}
  	    }
  	    return rid;
  	}
      }
docs: write_attribute_asynch_i - access limited to package Group