@Override
    public ArmeriaResteasyClientBuilder withConfig(Configuration config) {
        delegate.withConfig(config);
        return this;
    }
{@link ArmeriaJaxrsClientEngine} will always be set as an {@link ClientHttpEngine}.
@throws UnsupportedOperationException always
resteasy/src/main/java/com/linecorp/armeria/client/resteasy/ArmeriaResteasyClientBuilder.java