FileUserType::detectType

static function detectType($value)
{
	if (is_string($value) && mb_substr($value, 0, 1) == self::NEW_FILE_PREFIX)
	{
		return [self::TYPE_NEW_OBJECT, mb_substr($value, 1)];
	}

	return [self::TYPE_ALREADY_ATTACHED, (int)$value];
}