code: public void setQuickReply(String content_type, String title, String payload, String image_url)
      {
          HashMap<String, String> quick_reply = new HashMap<String, String>();
          quick_reply.put("content_type", content_type);
          quick_reply.put("title", title);
          quick_reply.put("payload", payload);
          quick_reply.put("image_url", image_url);
          this.message_quick_replies.add(quick_reply);
      }
docs: Set Quick Reply
  
  @param content_type the content type
  @param title the title
  @param payload the payload flag
  @param image_url the image URL