fixes error with server side validation + data tyep editor, ensures template controller and data type controller inherit from BackOfficeNotificationsController, ensures BackOfficeNotificationsController is attributed with PrefixlessBodyModelValidator

src/Umbraco.Web/Models/ContentEditing/GetAvailableCompositionsFilter.cs

@@ -3,7 +3,18 @@ namespace Umbraco.Web.Models.ContentEditing
     public class GetAvailableCompositionsFilter
     {
         public int ContentTypeId { get; set; }
+
+        /// <summary>
+        /// This is normally an empty list but if additional property type aliases are passed in, any content types that have these aliases will be filtered out.
+        /// This is required because in the case of creating/modifying a content type because new property types being added to it are not yet persisted so cannot
+        /// be looked up via the db, they need to be passed in.
+        /// </summary>
         public string[] FilterPropertyTypes { get; set; }
+
+        /// <summary>
+        /// This is normally an empty list but if additional content type aliases are passed in, any content types containing those aliases will be filtered out
+        /// along with any content types that have matching property types that are included in the filtered content types
+        /// </summary>
         public string[] FilterContentTypes { get; set; }
     }
 }

src/Umbraco.Web/Models/ContentEditing/TemplateDisplay.cs

@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 namespace Umbraco.Web.Models.ContentEditing
 {
     [DataContract(Name = "template", Namespace = "")]
-    public class TemplateDisplay
+    public class TemplateDisplay : INotificationModel
     {
         [DataMember(Name = "id")]
         public int Id { get; set; }
@@ -30,5 +30,11 @@ namespace Umbraco.Web.Models.ContentEditing
 
         [DataMember(Name = "masterTemplateAlias")]
         public string MasterTemplateAlias { get; set; }
+
+        /// <summary>
+        /// This is used to add custom localized messages/strings to the response for the app to use for localized UI purposes.
+        /// </summary>
+        [DataMember(Name = "notifications")]
+        public List<Notification> Notifications { get; private set; }
     }
 }