430960 sysem cache plugin modification

My site uses subdomains and multsite structure. The joomla system cache plugin has issues with caching multisite using subdomains. Page Cache caches the URL not including the domain so a homepage loaded for one site will get displayed for another. Need to build another page cache plugin (or modify the existing system-cache plugin) and intercept and extend the JCachePage class to make the cache id include the domain name. So when system cache (page cache)turned on, the homepage of a subdomain will load for the right sub-site.