https://docs.spring.io/spring-framework/docs/current/reference/html/languages.html#kotlin

2021
https://towardsdatascience.com/a-benchmark-of-spring-annotations-vs-kotlin-dsl-209f54294325
Arhipov - Kotlin Extensions in Spring Framework
    https://www.youtube.com/watch?v=0jWo3o7r-W4
2020
https://blog.jetbrains.com/kotlin/2020/08/the-state-of-kotlin-support-in-spring/