protected function validateMultiValue($value, array $attributes)
    {
        if (null === $value) {
            return array();
        }

        if (!is_array($value)) {
            return (array) $value;
        }

        if (!isset($attributes['multiple']) || !$attributes['multiple']) {
            throw new Exception\DomainException(sprintf(
                '%s does not allow specifying multiple selected values when the element does not have a multiple attribute set to a boolean true',
                __CLASS__
            ));
        }

        return $value;
    }