code: public static List<BitextRule> getBitextRules(Language source,
        Language target, File externalBitextRuleFile) throws IOException, ParserConfigurationException, SAXException {
      List<BitextRule> bRules = new ArrayList<>();
      //try to load the bitext pattern rules for the language...
      BitextPatternRuleLoader ruleLoader = new BitextPatternRuleLoader();          
      String name = "/" + target.getShortCode() + "/bitext.xml";
      if (JLanguageTool.getDataBroker().ruleFileExists(name)) {
        InputStream is = JLanguageTool.getDataBroker().getFromRulesDirAsStream(name);
        if (is != null) {
          bRules.addAll(ruleLoader.getRules(is, name));
        }
      }
      if (externalBitextRuleFile != null) {
        bRules.addAll(ruleLoader.getRules(new FileInputStream(externalBitextRuleFile), externalBitextRuleFile.getAbsolutePath()));
      }
      
      //load the false friend rules in the bitext mode:
      FalseFriendsAsBitextLoader fRuleLoader = new FalseFriendsAsBitextLoader();
      String falseFriendsFile = "/false-friends.xml";
      List<BitextPatternRule> rules = fRuleLoader.getFalseFriendsAsBitext(falseFriendsFile, source, target);
      bRules.addAll(rules);
  
      //load Java bitext rules:
      bRules.addAll(getAllBuiltinBitextRules(source, null));
      return bRules;
    }
docs: Gets default bitext rules for a given pair of languages
  @param source  Source language.
  @param target  Target language.
  @param externalBitextRuleFile external file with bitext rules
  @return  List of Bitext rules
  @since 2.9