Fix Deserialization of defaultConfig from package.manifest

src/Umbraco.Core/PropertyEditors/ConfigurationEditor.cs

@@ -10,6 +10,7 @@ namespace Umbraco.Cms.Core.PropertyEditors
     /// <summary>
     /// Represents a data type configuration editor.
     /// </summary>
+    [DataContract]
     public class ConfigurationEditor : IConfigurationEditor
     {
         private IDictionary<string, object> _defaultConfiguration;

src/Umbraco.Core/PropertyEditors/IConfigurationEditor.cs

@@ -1,4 +1,5 @@
 using System.Collections.Generic;
+using System.Runtime.Serialization;
 using Umbraco.Cms.Core.Serialization;
 
 namespace Umbraco.Cms.Core.PropertyEditors
@@ -11,6 +12,7 @@ namespace Umbraco.Cms.Core.PropertyEditors
         /// <summary>
         /// Gets the fields.
         /// </summary>
+        [DataMember(Name = "fields")]
         List<ConfigurationField> Fields { get; }
 
         /// <summary>
@@ -22,6 +24,7 @@ namespace Umbraco.Cms.Core.PropertyEditors
         /// equivalent of an actual configuration object (ie an instance of <c>TConfiguration</c>, obtained
         /// via <see cref="ToConfigurationEditor"/>.</para>
         /// </remarks>
+        [DataMember(Name = "defaultConfig")]
         IDictionary<string, object> DefaultConfiguration { get; }
 
         /// <summary>