code: private static void findTranslateOptions(String[] args, Map<String,Transformer> suffix_rules)
          throws ProblemException, ProblemException {
  
          for (int i = 0; i<args.length; ++i) {
              if (args[i].equals("-tr")) {
                  if (i+1 >= args.length) {
                      throw new ProblemException("You have to specify a translate rule following -tr.");
                  }
                  String s = args[i+1];
                  checkTranslatePattern(s);
                  int ep = s.indexOf("=");
                  String suffix = s.substring(0,ep);
                  String classname = s.substring(ep+1);
                  if (suffix_rules.get(suffix) != null) {
                      throw new ProblemException("You have already specified a "+
                                                "rule for the suffix "+suffix);
                  }
                  if (s.equals(".class")) {
                      throw new ProblemException("You cannot have a translator for .class files!");
                  }
                  if (s.equals(".java")) {
                      throw new ProblemException("You cannot have a translator for .java files!");
                  }
                  String extra = null;
                  int exp = classname.indexOf(",");
                  if (exp != -1) {
                      extra = classname.substring(exp+1);
                      classname = classname.substring(0,exp);
                  }
                  try {
                      Class<?> cl = Class.forName(classname);
                      Transformer t = (Transformer)cl.newInstance();
                      t.setExtra(extra);
                      suffix_rules.put(suffix, t);
                  }
                  catch (Exception e) {
                      throw new ProblemException("Cannot use "+classname+" as a translator!");
                  }
              }
          }
      }
docs: Scan the arguments to find the option (-tr) that setup translation rules to java source
  from different sources. For example: .properties are translated using CompileProperties
  The found translators are stored as suffix rules.