private TubeMQResult handleSubscribeRequest(String req) {
        return masterService.baseRequestMaster(gson.fromJson(req, SetSubscribeReq.class));
    }
Handles 'SUBSCRIBE' method request.

@param req The JSON request
@return TubeMQResult based on the request
inlong-tubemq/tubemq-manager/src/main/java/org/apache/inlong/tubemq/manager/controller/topic/TopicWebController.java