https://projects.spring.io/spring-statemachine/
https://github.com/spring-projects/spring-statemachine

https://docs.spring.io/spring-statemachine/docs/2.1.0.RELEASE/reference/htmlsingle/#state-machine-via-builder

2020
https://spring.io/blog/2020/12/11/spring-statemachine-3-0-0-rc1-released
2019
https://habr.com/ru/post/462371/
https://habr.com/ru/post/440788/