static <T> SimpleLoadBalancer<T> ofRoundRobin(Iterable<? extends T> candidates) {
        requireNonNull(candidates, "candidates");
        return new RoundRobinLoadBalancer<>(candidates);
    }
Returns a {@link LoadBalancer} that selects a candidate using the round-robin strategy.
core/src/main/java/com/linecorp/armeria/common/loadbalancer/LoadBalancer.java