code: public CLDR.Locale match(MetaLocale locale) {
      MetaLocale result = availableBundlesMap.get(locale);
      MetaLocale maxBundleId = null;
      if (result == null) {
        // If the locale isn't expanded, do that here by adding likely subtags.
        // For the vast majority of cases this code shouldn't be executed, since
        // we've indexed permutations of locales to create a static mapping to
        // bundle identifiers.
        maxBundleId = languageResolver.addLikelySubtags(locale);
        MetaLocale minBundleId = languageResolver.removeLikelySubtags(maxBundleId);
        result = availableBundlesMap.get(minBundleId);
      }
      if (result == null) {
        // Fallback necessary to find best match for language tags that have
        // invalid fields, e.g. those with an unknown region, etc.
        MetaLocale key = maxBundleId.copy();
        for (int flags : LanguageResolver.MATCH_ORDER) {
          LanguageResolver.set(maxBundleId, key, flags);
          result = availableBundlesMap.get(key);
          if (result != null && result.hasLanguage()) {
            return result;
          }
        }
      }
      return result != null ? result : availableBundlesMap.get((MetaLocale)CLDR.Locale.en);
    }
docs: Given a MetaLocale object (internal to CLDR), return the best available
  CLDR bundle identifier.