code: public static List<InetSocketAddress> getAddresses(Configuration conf,
        String defaultAddress, String... keys) {
      return getAddresses(conf, getNameServiceIds(conf), defaultAddress, keys);
    }
docs: Returns list of InetSocketAddress for a given set of keys.
  @param conf configuration
  @param defaultAddress default address to return in case key is not found
  @param keys Set of keys to look for in the order of preference
  @return list of InetSocketAddress corresponding to the key