public Function<? super EventLoopGroup,
            ? extends AddressResolverGroup<? extends InetSocketAddress>> addressResolverGroupFactory() {

        return get(ADDRESS_RESOLVER_GROUP_FACTORY);
    }
Returns the factory that creates an {@link AddressResolverGroup} which resolves remote addresses into
{@link InetSocketAddress}es.
core/src/main/java/com/linecorp/armeria/client/ClientFactoryOptions.java