code: public void mute(final AVIMConversationCallback callback) {
      if (StringUtil.isEmpty(getConversationId())) {
        if (null != callback) {
          callback.internalDone(new AVException(AVException.INVALID_QUERY, "ConversationId is empty"));
        } else {
          LOGGER.w("ConversationId is empty");
        }
        return;
      }
      InternalConfiguration.getOperationTube().participateConversation(client.getClientId(), conversationId, getType(),
              null, Conversation.AVIMOperation.CONVERSATION_MUTE, callback);
    }
docs: 静音，客户端拒绝收到服务器端的离线推送通知
  
  @param callback