_onQueueEnded(event) {
        if (event === 'init') {
            this.finished = true;

            const now = Date.now();
            logging.info(`URL Service ready in ${now - this.lastInitStartTime}ms`);
            metrics.metric('url-service', now - this.lastInitStartTime);
        }
    }
@description The queue will notify us if the queue has ended with an event.
@param {String} event
@private