ASP.NET MVC 3.0 : Configure OutputCache attribute to produce Cache-Control: public -

i want outputcache attribute produce header cache-control set public. how do that?

maybe code attribute help

using system; using system.web; using system.web.mvc;      public class cachefilterattribute : actionfilterattribute {         /// <summary>         /// gets or sets cache duration in seconds. default 10 seconds.         /// </summary>         /// <value>the cache duration in seconds.</value>         public int duration {             get;             set;         }          public cachefilterattribute() {             duration = 30;         }          public override void onactionexecuted(actionexecutedcontext filtercontext) {             if (duration <= 0) return;              httpcachepolicybase cache = filtercontext.httpcontext.response.cache;             timespan cacheduration = timespan.fromseconds(duration);              cache.setcacheability(httpcacheability.public);             cache.setexpires(datetime.now.add(cacheduration));             cache.setmaxage(cacheduration);             cache.appendcacheextension("must-revalidate, proxy-revalidate");         }     } 

and use [cachefilter] instead of outputcache