Added IsPublished(culture) to IPublishedContent

src/Umbraco.Web/PublishedCache/PublishedMember.cs

@@ -78,6 +78,8 @@ namespace Umbraco.Web.PublishedCache
 
         public override bool IsDraft(string culture = null) => false;
 
+        public override bool IsPublished(string culture = null) => true;
+
         public override IPublishedContent Parent => null;
 
         public override IEnumerable<IPublishedContent> Children => Enumerable.Empty<IPublishedContent>();