为什么要把点替换成下划线

    public void send(final MQDestination destination, Message message, Callback callback) {
        ExecutorTemplate template = new ExecutorTemplate(sendExecutor);
        try {
            if (!StringUtils.isEmpty(destination.getDynamicTopic())) {
                // 动态topic
                Map<String, Message> messageMap = MQMessageUtils
                    .messageTopics(message, destination.getTopic(), destination.getDynamicTopic());

                for (Map.Entry<String, com.alibaba.otter.canal.protocol.Message> entry : messageMap.entrySet()) {
                    final String topicName = entry.getKey().replace('.', '_');
                    final com.alibaba.otter.canal.protocol.Message messageSub = entry.getValue();

                    template.submit(() -> send(destination, topicName, messageSub));
                }

                template.waitForResult();
            } else {
                send(destination, destination.getTopic(), message);
            }
            callback.commit();
        } catch (Throwable e) {
            logger.error(e.getMessage(), e);
            callback.rollback();
        } finally {
            template.clear();
        }
    }