add ignore attribute

MediaBrowser.Controller/Entities/Audio/MusicArtist.cs

@@ -72,6 +72,7 @@ namespace MediaBrowser.Controller.Entities.Audio
             return LibraryManager.GetItemList(query);
         }
 
+        [IgnoreDataMember]
         protected override IEnumerable<BaseItem> ActualChildren
         {
             get

MediaBrowser.Controller/Entities/CollectionFolder.cs

@@ -188,6 +188,7 @@ namespace MediaBrowser.Controller.Entities
         /// Our children are actually just references to the ones in the physical root...
         /// </summary>
         /// <value>The actual children.</value>
+        [IgnoreDataMember]
         protected override IEnumerable<BaseItem> ActualChildren
         {
             get { return GetActualChildren(); }

MediaBrowser.Controller/Entities/Folder.cs

@@ -285,6 +285,7 @@ namespace MediaBrowser.Controller.Entities
         /// Gets the actual children.
         /// </summary>
         /// <value>The actual children.</value>
+        [IgnoreDataMember]
         protected virtual IEnumerable<BaseItem> ActualChildren
         {
             get