sealed interface AsyncReturn<V> {
    record Success<V>(V result) implements AsyncReturn<V> { }
    record Failure<V>(Throwable cause) implements AsyncReturn<V> { }
    record Timeout<V>() implements AsyncReturn<V> { }
    record Interrupted<V>() implements AsyncReturn<V> { }
}

...

interface Future<V> {
    AsyncReturn<V> get();
}

AsyncResult<V> r = future.get();
switch (r) {
    case Success(var result): ...
    case Failure(Throwable cause): ...
    case Timeout(), Interrupted(): ...
}