public static void buildContact(ContactEntry contact, 
      List<String> parameters) {
    for (String string : parameters) {
      if (!string.startsWith("--")) {
        throw new IllegalArgumentException("unknown argument: " + string);
      }
      String param = string.substring(2);
      String params[] = param.split("=", 2);
      if (params.length != 2) {
        throw new IllegalArgumentException("badly formated argument: " 
            + string);
      }
      ElementHelper helper = find(params[0]);
      if (helper == null) {
        throw new IllegalArgumentException("unknown argument: " + string);
      }
      helper.parse(contact, new ElementParser(params[1]));
    }
  }