public EndpointSelectionStrategy build() {
        validate();
        final Supplier<EventExecutor> executorSupplier;
        final EventExecutor executor = executor();
        if (executor != null) {
            executorSupplier = () -> executor;
        } else {
            executorSupplier = () -> CommonPools.workerGroup().next();
        }

        return new WeightRampingUpStrategy(weightTransition(), executorSupplier, rampingUpIntervalMillis(),
                                           totalSteps(), rampingUpTaskWindowMillis(), timestampFunction(),
                                           ticker());
    }
Returns a newly-created weight ramping up {@link EndpointSelectionStrategy} which ramps the weight of
newly added {@link Endpoint}s. The {@link Endpoint} is selected using weighted random distribution.
core/src/main/java/com/linecorp/armeria/client/endpoint/WeightRampingUpStrategyBuilder.java