return metaDataMap;
    }

    /**
     * Adds a child URL discovered from this response.
     *
     * @param url the child URL to add
     */
    public void addChildUrl(final RequestData url) {
        childUrlSet.add(url);
    }

    /**
     * Removes a child URL from this response.
     *
     * @param url the child URL to remove
     */