在API Manager产品（WSO2和Apigee）中，可以配置节流，但如何在内部实现？
我尝试通过以下代码，但找不到实现：https://github.com/wso2/carbon-apimgt/tree/master/components/apimgt
这里有一些资源。
https://wso2.com/library/articles/2016/06/article-introducing-new-throttling-feature-in-wso2-api-manager-2.0/
https://wso2.com/library/articles/2016/10/article-scalable-traffic-manager-deployment-patterns-for-wso2-api-manager-part-1/
https://wso2.com/library/articles/2016/10/article-scalable-traffic-manager-deployment-patterns-for-wso2-api-manager-part-2/
http://sanjeewamalalgoda.blogspot.com/2016/09/wso2-api-manager-new-throttling-how.html
https://chamindias.wordpress.com/2019/07/16/throttling-in-wso2-api-manager/
https://github.com/wso2/carbon-apimgt/tree/master/components/apimgt/org.wso2.carbon.apimgt.throttling.service
https://github.com/wso2/carbon-apimgt/tree/master/components/apimgt/org.wso2.carbon.apimgt.jms.listener
https://github.com/wso2/carbon-apimgt/tree/master/components/apimgt/org.wso2.carbon.apimgt.throttling.siddhi.extension