public DnsResolverGroupBuilder autoRefreshBackoff(Backoff refreshBackoff) {
        autoRefreshBackoff = requireNonNull(refreshBackoff, "refreshBackoff");
        return this;
    }
Sets the {@link Backoff} which is used when the {@link DnsNameResolver} fails to update the cache.
core/src/main/java/com/linecorp/armeria/client/DnsResolverGroupBuilder.java