public Set<TransientServiceOption> transientServiceOptions() {
        return transientServiceOptions;
    }
Returns the {@link Set} of {@link TransientServiceOption}s that are enabled for the {@link #service()}.
This method always returns {@link TransientServiceOption#allOf()} for a non-{@link TransientService}
because only a {@link TransientService} can opt in and out using
{@link TransientServiceBuilder#transientServiceOptions(TransientServiceOption...)}.
core/src/main/java/com/linecorp/armeria/server/ServiceConfig.java