@Nonnull
    default Promise<Void> thenAcceptSync(@Nonnull Consumer<? super V> action) {
        return thenApplySync(Delegates.consumerToFunction(action));
    }
Returns a new Promise that, when this promise completes normally, is
executed with this promise's result as the argument to the given
action.

@param action the action to perform before completing the returned future
@return the new promise
helper/src/main/java/me/lucko/helper/promise/Promise.java