public ClientFactoryBuilder domainNameResolverCustomizer(
            Consumer<? super DnsResolverGroupBuilder> dnsResolverGroupCustomizer) {
        requireNonNull(dnsResolverGroupCustomizer, "dnsResolverGroupCustomizer");
        checkState(!options.containsKey(ClientFactoryOptions.ADDRESS_RESOLVER_GROUP_FACTORY),
                   "addressResolverGroupFactory() and domainNameResolverCustomizer() are mutually exclusive.");
        if (this.dnsResolverGroupCustomizer == null) {
            //noinspection unchecked
            this.dnsResolverGroupCustomizer = (Consumer<DnsResolverGroupBuilder>) dnsResolverGroupCustomizer;
        } else {
            this.dnsResolverGroupCustomizer =
                    this.dnsResolverGroupCustomizer.andThen(dnsResolverGroupCustomizer);
        }
        return this;
    }
Adds the specified {@link Consumer} which customizes the given {@link DnsNameResolverBuilder}.
This method is useful when you want to change the behavior of the default domain name resolver, such as
changing the DNS server list.

@throws IllegalStateException if {@link #addressResolverGroupFactory(Function)} was called already.
core/src/main/java/com/linecorp/armeria/client/ClientFactoryBuilder.java