docs: public static List<Locale> languagesByCountry(String countryCode)
      {
          if (countryCode == null)
          {
              return Collections.emptyList();
          }
          List<Locale> langs = LANGUAGES_BY_COUNTRY.get(countryCode);
          if (langs == null)
          {
              langs = new ArrayList<Locale>();
              List<Locale> locales = availableLocaleList();
              for (int i = 0; i < locales.size(); i++)
              {
                  Locale locale = locales.get(i);
                  if (countryCode.equals(locale.getCountry()) &&
                          locale.getVariant().length() == 0)
                  {
                      langs.add(locale);
                  }
              }
              langs = Collections.unmodifiableList(langs);
              LANGUAGES_BY_COUNTRY.putIfAbsent(countryCode, langs);
              langs = LANGUAGES_BY_COUNTRY.get(countryCode);
          }
          return langs;
      }