https://www.kotlinprimer.com/basics/functions-variables/functions/

Pro Spring Boot 3 with Kotlin 3rd ed
Kotlin an Illustrated Guide ru
Kotlin in Action 2nd ed                             -  65  (of  849)
    ch 14, 15 - coro?

spring
https://kotlinlang.org/docs/jvm-get-started-spring-boot.html
https://spring.io/guides/tutorials/spring-boot-kotlin
https://docs.spring.io/spring-framework/docs/current/kdoc-api/

?
https://spring.io/guides/tutorials/spring-webflux-kotlin-rsocket

todo: use:
kt connekt
    pl/kt/tools/http/connekt.txt