got legacy tree icons showing up now, added a couple of filters for this to work.

src/Umbraco.Core/Serialization/JsonCreationConverter.cs

@@ -4,33 +4,6 @@ using Newtonsoft.Json.Linq;
 
 namespace Umbraco.Core.Serialization
 {
-    /// <summary>
-    /// This is used in order to deserialize a json object on a property into a json string since the property's type is 'string'
-    /// </summary>
-    internal class JsonToStringConverter : JsonConverter
-    {
-        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
-        {
-            throw new NotImplementedException();
-        }
-
-        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
-        {
-            if (reader.ValueType == typeof(string))
-            {
-                return reader.Value;
-            }
-            // Load JObject from stream
-            JObject jObject = JObject.Load(reader);
-            return jObject.ToString();
-        }
-
-        public override bool CanConvert(Type objectType)
-        {
-            return typeof(string).IsAssignableFrom(objectType);
-        }
-    }
-
     internal abstract class JsonCreationConverter<T> : JsonConverter
     {
         /// <summary>