Moved BackOfficeNotificationsController to netcore

src/Umbraco.Web.BackOffice/Controllers/BackOfficeNotificationsController.cs

@@ -0,0 +1,16 @@
+using Microsoft.AspNetCore.Mvc;
+using Umbraco.Web.WebApi.Filters;
+
+namespace Umbraco.Web.Editors
+{
+    /// <summary>
+    /// An abstract controller that automatically checks if any request is a non-GET and if the
+    /// resulting message is INotificationModel in which case it will append any Event Messages
+    /// currently in the request.
+    /// </summary>
+    [TypeFilter(typeof(AppendCurrentEventMessagesAttribute))]
+    public abstract class BackOfficeNotificationsController : UmbracoAuthorizedJsonController
+    {
+
+    }
+}