Konrad Kamiński I turn this issue into a global coroutine support one, since there may be other areas than ListenableFuture impacted as shown by your spring-kotlin-coroutine project.
Did you experiment with coroutines + Spring WebFlux? After reading the guide to reactive streams with coroutines, it seems to me this is something worth to explore if we can leverage the existing Reactor based infrastructure of Spring WebFlux (via annotation or functional API) to provide the ability to use imperative style code for those who are not confortable with functional APIs.
That said we really need to experiment in order to see how this work with backpressure, see if it can enable easily to implement custom operator as advertised, etc.
I am quite confident about the ListenableFuture / Mono use case but the Flux use case is less obvious to me.
Any sample WebFlux + coroutine application example could help to move this topic forward.