code: public static String makeLocale(String lang, String country) {
      if ((lang == null) || (lang.length() == 0)) {
        return localeInfoDefaultDefault;
      }
  
      if ((country == null) || (country.length() == 0)) {
        return localeInfoDefaultDefault;
      }
  
      return lang + "_" + country;
    }
docs: If either the lang or country is null we provide a default value for
  the whole locale. Otherwise we construct one.
  
  @param lang
  @param country
  @return locale