code: protected static void addLanguageAlias(String rawType, String rawReplacement) {
      LanguageAlias type = LanguageAlias.parse(rawType);
      LanguageAlias replacement = LanguageAlias.parse(rawReplacement);
      String language = type.language();
      List<Pair<LanguageAlias, LanguageAlias>> aliases = LANGUAGE_ALIAS_MAP.get(language);
      if (aliases == null) {
        aliases = new ArrayList<>();
        LANGUAGE_ALIAS_MAP.put(language, aliases);
      }
      aliases.add(Pair.pair(type, replacement));
    }
docs: Add a language alias entry.