public Site addCookie(String domain, String name, String value) {
        if (!cookies.containsKey(domain)){
            cookies.put(domain,new HashMap<String, String>());
        }
        cookies.get(domain).put(name, value);
        return this;
    }
Add a cookie with specific domain.

@param domain domain
@param name name
@param value value
@return this
webmagic-core/src/main/java/us/codecraft/webmagic/Site.java