/**
  * Validates an option.
  * 
  * @param	string		$key		option name
  * @param	array		$option		option data
  */
 protected function validateOption($key, $option)
 {
     parent::validateOption($key, $option);
     if ($option['required'] && empty($this->activeOptions[$key]['optionValue'])) {
         throw new UserInputException($option['optionName']);
     }
 }