protected void writeActionInputArguments(
      Document d, Element actionRequestElement, ActionInvocation actionInvocation) {

    for (ActionArgument argument : actionInvocation.getAction().getInputArguments()) {
      log.fine("Writing action input argument: " + argument.getName());
      String value =
          actionInvocation.getInput(argument) != null
              ? actionInvocation.getInput(argument).toString()
              : "";
      XMLUtil.appendNewElement(d, actionRequestElement, argument.getName(), value);
    }
  }