public @interface Async

Runs this method on another thread; the caller returns at once.

The method returns void, or a java.util.concurrent.Future – typically com.codename1.backend.AsyncResult.of(value) – which the caller receives immediately and which completes when the work does. Anything else is a build error, because a caller could not receive it.

The build rewrites the compiled method so that it packages its arguments into a task and hands the task to the named executor; there is no proxy, so this works however the method is called. An exception from a void method is logged and recorded on the current span, since nobody is waiting for it.