code: private void findCopyOptions(String[] args, Map<String,Transformer> suffix_rules)
          throws ProblemException, ProblemException {
  
          for (int i = 0; i<args.length; ++i) {
              if (args[i].equals("-copy")) {
                  if (i+1 >= args.length) {
                      throw new ProblemException("You have to specify a translate rule following -tr.");
                  }
                  String s = args[i+1];
                  checkCopyPattern(s);
                  if (suffix_rules.get(s) != null) {
                      throw new ProblemException("You have already specified a "+
                                                "rule for the suffix "+s);
                  }
                  if (s.equals(".class")) {
                      throw new ProblemException("You cannot have a copy rule for .class files!");
                  }
                  if (s.equals(".java")) {
                      throw new ProblemException("You cannot have a copy rule for .java files!");
                  }
                  suffix_rules.put(s, javac_state.getCopier());
              }
          }
      }
docs: Scan the arguments to find the option (-copy) that setup copying rules into the bin dir.
  For example: -copy .html
  The found copiers are stored as suffix rules as well. No translation is done, just copying.