code: @Override
  	public FbBotMillResponse createResponse(MessageEnvelope envelope) {
  		FbBotMillResponse response = null;
  
  		switch (attachmentType) {
  		case FILE:
  			response = ReplyFactory.addFileAttachment(url).build(envelope);
  			break;
  		case IMAGE:
  			response = ReplyFactory.addImageAttachment(url).build(envelope);
  			break;
  		case AUDIO:
  			response = ReplyFactory.addAudioAttachment(url).build(envelope);
  			break;
  		case VIDEO:
  			response = ReplyFactory.addVideoAttachment(url).build(envelope);
  			break;
  		default:
  			String message = "Illegal attachment of type [ " + attachmentType.name() + " ] for AttachmentAutoReply";
  			logger.error(message);
  			throw new BotMillIllegalAttachmentException(message);
  		}
  		return response;
  	}
docs: {@inheritDoc} Replies with an attachment.