public final SELF weightTransition(WeightTransition<T> transition) {
        weightTransition = requireNonNull(transition, "transition");
        return self();
    }
Sets the {@link WeightTransition} which will be used to compute the weight at each step while
ramping up. {@link WeightTransition#linear()} is used by default.
core/src/main/java/com/linecorp/armeria/common/loadbalancer/AbstractRampingUpLoadBalancerBuilder.java