code: private void processMessageReceipt(String msgId, String conversationId, int convType, long timestamp) {
      Object messageCache =
              MessageReceiptCache.get(session.getSelfPeerId(), msgId);
      if (messageCache == null) {
        return;
      }
      Message m = (Message) messageCache;
      AVIMMessage msg =
              new AVIMMessage(conversationId, session.getSelfPeerId(), m.timestamp, timestamp);
      msg.setMessageId(m.id);
      msg.setContent(m.msg);
      msg.setMessageStatus(AVIMMessage.AVIMMessageStatus.AVIMMessageStatusReceipt);
      AVConversationHolder conversation = session.getConversationHolder(conversationId, convType);
      conversation.onMessageReceipt(msg);
    }
docs: 处理 v2 版本中 message 的 rcp 消息
  @param msgId
  @param conversationId
  @param timestamp