@UnstableApi
    public BlockingWebClient blockingWebClient(Consumer<WebClientBuilder> webClientCustomizer) {
        requireNonNull(webClientCustomizer, "webClientCustomizer");
        return delegate.blockingWebClient(webClientCustomizer);
    }
Returns a newly created {@link BlockingWebClient} configured by
{@link #configureWebClient(WebClientBuilder)} and then the specified customizer.
junit4/src/main/java/com/linecorp/armeria/testing/junit4/server/ServerRule.java