Add ElementType.TYPE to ActorType to enable it in Kotlin

[LionTao]

Describe the proposal

Hi, I want to use the actor model with Kotlin. Currently, the ActorType annotation in java is targeted at ElementType.TYPE_USE which is incompatible with kotlin interface.
Adding ElementType.TYPE to the annotation target field should work. Can we add it?

[artursouza]

Overall I am inclined. But what would be the difference?

[LionTao]

Overall I am inclined. But what would be the difference?

That would allow writing actor interfaces in kotlin.
Currently I want to write my actor implemtation in kotlin but I have to write a java actor interface to use the java sdk features.

[mukundansundar]

@LionTao Will you be able to contribute a PR for this change?

[LionTao]

@LionTao Will you be able to contribute a PR for this change?

Of course, created #812

[mukundansundar]

@LionTao Could you provide some documentation link in the PR or in this issue which explains why ElementType.Type is needed for Kotlin?

[LionTao]

@LionTao Could you provide some documentation link in the PR or in this issue that explains why ElementType.Type is needed for Kotlin?

According to Kotlin docs, it seems currently kotlin lacks some native java ElementType enum values.

For my project, rewriting the ActorType annotation class with ElementType.TYPE will let it annotate a kotlin interface. Otherwise, the kotlin compiler throws an error that says This annotation is not applicable to target 'interface'.