public void addTargetRequest(String requestString) {
        if (StringUtils.isBlank(requestString) || requestString.equals("#")) {
            return;
        }
        requestString = UrlUtils.canonicalizeUrl(requestString, url.toString());
        targetRequests.add(new Request(requestString));
    }
add url to fetch

@param requestString requestString
webmagic-core/src/main/java/us/codecraft/webmagic/Page.java