public function queueForReplacement($originalUrl, $expandedUrl, $trackingUrl, $shortenedTrackingUrl)
    {
        $this->replacementUrls[$originalUrl][] = array(
            self::URL_TYPE_EXPANDED => $expandedUrl,
            self::URL_TYPE_TRACKED => $trackingUrl,
            self::URL_TYPE_SHORTENED_TRACKED => $shortenedTrackingUrl
        );
    }