Our team adopted Kotlin on back-end as soon as 1.0 came out 🙂 Currently 90% of new code is written in Kotlin and old code is also some-times converted on a case by case basis. 🙂
Spring boot: 1.5.x, Spring Platform: Brussels-SR3
Me being the lead and loving Kotlin helped of course 😄
No official support in current stable version of Spring is a bummer, but I can't say it creates too many problems, if any. After you get accustomed to a couple of quirks (like need to
open
, occasional
lateinit var
, etc.), it is a very pleasurable experience.