@Override
    public void handlerPlugin(final PluginData pluginData) {
        MqttServerConfiguration configuration = GsonUtils.getInstance().fromJson(pluginData.getConfig(), MqttServerConfiguration.class);
        configuration.afterPropertiesSet();
        if (pluginData.getEnabled()) {
            server.init();
            server.start();
        } else {
            if (isPortUsing(configuration.getPort())) {
                server.shutdown();
            }
        }
    }
The type Mqtt plugin data handler.
shenyu-plugin/shenyu-plugin-proxy/shenyu-plugin-mqtt/src/main/java/org/apache/shenyu/plugin/mqtt/handler/MqttPluginDataHandler.java