add ActorContext.getChild that returns Optional

[rkuhn]

This works better with Java 8 lambdas (orElseGet instead of getOrElse).

[patriknw]

would be nice, but there is already a def getChild(name: String): ActorRef in AbstractActorContext. Rather messy to add yet another variant (getChildOptional).

Optional.ofNullable(getContext().getChild(name)) is good enough in my opinion.

[He-Pin]

Still found I need this sometime, maybe with a getChildOptional? Or change it in Akka 3?

[patriknw]

you could also use Akka Typed