U4-8938 [OutputCache] headers changed from Cache-Control: public to private

src/Umbraco.Web/Routing/PublishedContentRequest.cs

@@ -589,13 +589,10 @@ namespace Umbraco.Web.Routing
         /// <summary>
         /// Gets or sets the <c>System.Web.HttpCacheability</c>
         /// </summary>
-        /// <remarks>Is set to <c>System.Web.HttpCacheability.Private</c>  by default, which is the ASP.NET default.</remarks>
-        private HttpCacheability _cacheability = HttpCacheability.Private;
-        internal HttpCacheability Cacheability
-        {
-            get { return _cacheability; }
-            set { _cacheability = value; }
-        }
+        // Note: we used to set a default value here but that would then be the default
+        // for ALL requests, we shouldn't overwrite it though if people are using [OutputCache] for example
+        // see: https://our.umbraco.org/forum/using-umbraco-and-getting-started/79715-output-cache-in-umbraco-752
+        internal HttpCacheability Cacheability { get; set; }
 
         /// <summary>
         /// Gets or sets a list of Extensions to append to the Response.Cache object

src/Umbraco.Web/UmbracoModule.cs

@@ -324,7 +324,8 @@ namespace Umbraco.Web
                 () => pcr.IsRedirect ? (pcr.IsRedirectPermanent ? "permanent" : "redirect") : "none",
                 () => pcr.Is404 ? "true" : "false", () => pcr.ResponseStatusCode);
             
-            response.Cache.SetCacheability(pcr.Cacheability);
+            if(pcr.Cacheability != default(HttpCacheability))
+                response.Cache.SetCacheability(pcr.Cacheability);
 
             foreach (var cacheExtension in pcr.CacheExtensions)
                 response.Cache.AppendCacheExtension(cacheExtension);