@Override
        public RocketMQLocalTransactionState executeLocalTransaction(Message msg, Object arg) {
            System.out.printf("ExtTransactionListenerImpl executeLocalTransaction and return UNKNOWN. \n");
            return RocketMQLocalTransactionState.UNKNOWN;
        }
Producer, using RocketMQTemplate sends a variety of messages
rocketmq-spring-boot-samples/rocketmq-produce-demo/src/main/java/org/apache/rocketmq/samples/springboot/ProducerApplication.java