AsFuture Compiler plugin

This Kotlin compiler plugin is meant to generate Java friendly APIs based on suspend code defined in commonMain. Drawing inspiration from several projects, and techniques out there.

Usage

class MyService : CoroutineScope by scope, AutoCloseable {
  override val coroutineContext: CoroutineContext = Dispatchers.Default
  
  @AsFuture
  suspend fun example(): Int {
    delay(1000)
    return 42
  }

  override fun close() = runBlocking {
    scope.cancelAndJoin()
  }
}

This will generate a Future based API for example:

class App {
    public static void main(String[] args) {
        MyService service = new MyService();
        service.example()
                .thenAccept(System.out::println);
    }
}

Whilst from Kotlin (Multiplatform) example will remain our originally defined suspend function. This happens by applying following techniques:

1. The example Java function is generated in jvmMain, and uses CoroutineScope to launch a future.
2. The newly generated Java function is annotated with @Deprecated("Only callable from Java", level = DeprecationLevel.HIDDEN) such that we cannot see this function from the Kotlin API.
3. The original example function gets @JvmName to exampleSuspend.

This gives us a Java API that support the reactive nature of suspend without having to rely on runBlocking (which doesn't exist for JVM), and we can still turn it into blocking using get. Which for Project Loom is non-blocking.

By exposing Future, we can also easily integrate with other languages on the JVM that support Future (e.g. Scala).