Expand Kotlin "coroutines and Mutiny" documentation

Description

Presently, the Kotlin guide includes a small section about using coroutines: “Kotlin coroutines and Mutiny”. However, the linked mutiny-kotlin documentation only describes the extension functions, not how to use coroutines with Kotlin.

Kotlin coroutines provide a imperative programming model that actually gets executed in an asynchronous, reactive manner. To simplify the interoperation between Mutiny and Kotlin there is the module io.smallrye.reactive:mutiny-kotlin, described here.

After fiddling around with the getting-started project, I was able to use coroutines (suspend fun) by switching to “reactive” libraries:

• quarkus-resteasy-reactive instead of quarkus-resteasy
• quarkus-resteasy-reactive-jackson instead of quarkus-resteasy-jackson
• io.smallrye.reactive:mutiny-kotlin instead of io.quarkus:quarkus-resteasy-mutiny
• potentially others?

Implementation ideas

Provide a minimal Kotlin coroutines example; or, make clear what dependencies, configuration, and code (if applicable) is required to use coroutines in your application.

[geoand]

Closing this as it seems to be covered by https://github.com/quarkusio/quarkus/pull/21416

[cescoffier]

We are recommending RestEasy reactive. See https://quarkus.io/blog/resteasy-reactive-smart-dispatch/.

RestEasy is still supported, but the reactive variant provides more features.