class ReservableRequestConcurrencyControllerOnlySingle extends AbstractReservableRequestConcurrencyController {

    @Override
    public Result tryRequest() {
        // No concurrency means we have to have 0 requests!
        if (lastSeenMaxValue(1) > 0) {
            if (casPendingRequests(0, 1)) {
                return Accepted;
            }
            return RejectedTemporary;
        }
        return RejectedPermanently;
    }

      ReservableRequestConcurrencyControllerOnlySingle(final Publisher<? extends ConsumableEvent<Integer>> maxConcurrency,
                                                     final Completable onClosing);

}