code: public void processMixNotification(String message, String defaultAction) {
      if (StringUtil.isEmpty(message)) {
        LOGGER.e("message is empty, ignore.");
      } else {
        String channel = getChannel(message);
        if (channel == null || !containsDefaultPushCallback(channel)) {
          channel = AVOSCloud.getApplicationId();
        }
  
        String action = getAction(message);
        if (null != action) {
          sendNotificationBroadcast(channel, message, defaultAction);
        } else {
          String clsName = getDefaultPushCallback(channel);
          if (StringUtil.isEmpty(clsName)) {
            LOGGER.e("className is empty, ignore.");
          } else {
            Intent intent = buildUpdateIntent(channel, message, null);
            ComponentName cn = new ComponentName(AVOSCloud.getContext(), clsName);
            intent.setComponent(cn);
            intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
            PendingIntent pendingIntent = PendingIntent.getActivity(AVOSCloud.getContext(), 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
            try {
              pendingIntent.send();
            } catch (PendingIntent.CanceledException e) {
              LOGGER.e("Ocurred PendingIntent.CanceledException", e);
            }
          }
        }
      }
    }
docs: 处理混合推送通知栏消息点击后的事件（现在支持小米、魅族，华为不支持）
  处理逻辑：如果是自定义 action 的消息点击事件，则发送 broadcast，否则按照 sdk 自有逻辑打开相应的 activity
  @param message