Restored type check for NuCache status controller.

Added service located extension method for retrieving creator and writer name.

src/Umbraco.Web/PublishedContentExtensions.cs

@@ -28,6 +28,7 @@ namespace Umbraco.Web
         private static UmbracoContext UmbracoContext => Current.UmbracoContext;
         private static ISiteDomainHelper SiteDomainHelper => Current.Factory.GetInstance<ISiteDomainHelper>();
         private static IVariationContextAccessor VariationContextAccessor => Current.VariationContextAccessor;
+        private static IUserService UserService => Current.Services.UserService;
 
         #region IsComposedOf
 
@@ -795,6 +796,20 @@ namespace Umbraco.Web
 
         #endregion
 
+        #region Writer and creator
+
+        public static string CreatorName(this IPublishedContent content)
+        {
+            return content.GetCreatorName(UserService);
+        }
+
+        public static string WriterName(this IPublishedContent content)
+        {
+            return content.GetWriterName(UserService);
+        }
+
+        #endregion
+
         #region Url
 
         /// <summary>