http://docs.spring.io/spring/docs/current/spring-framework-reference/html/mvc.html
https://spring.io/guides/gs/serving-web-content/

https://springframework.guru/spring-boot-web-application-part-4-spring-mvc/

RequestParam
https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestParam.html
https://stackoverflow.com/questions/39774427/springs-requestparam-with-enum