code: public void add(String name, String... values) {
      if (containsKey(name)) {
        List<String> list = get(name);
        for (String value: values) {
          list.add(value);
        }
      } else {
        put(name, values);
      }
    }
docs: Appends a list of values to the list for a parameter.
  @param name	the parameter
  @param values	the values to add to the list