static Backoff withoutDelay() {
        return NO_DELAY;
    }
Returns a {@link Backoff} that will never wait between attempts. In most cases, using back off
without delay is very dangerous. Please consider using {@link #exponential(long, long)} with
{@link #withJitter(double)} or {@link #fixed(long)} with pre calculated delay depending on the situation.
core/src/main/java/com/linecorp/armeria/client/retry/Backoff.java