public function validateLogoUrl($url)
    {
        if (empty($url)) {
            return true;
        }

        if (!is_string($url)) {
            $this->addError('url', 'Url must be a string');
            return false;
        }

        if (mb_strlen($url, 'UTF-8') > 255) {
            $this->addError('url', 'Url length has to be less or equal to 255');
            return false;
        }

        if (filter_var($url, FILTER_VALIDATE_URL) === false) {
            $this->addError('url', 'Url must contain protocol and domain name');
            return false;
        }

        return true;
    }