Fixes: #U4-1141 - IPropertyEditorValueConverter is not a plugin type and is searched for on app startup.

src/Umbraco.Core/CoreBootManager.cs

@@ -109,12 +109,11 @@ namespace Umbraco.Core
 				PluginManager.Current.ResolveActions());
 
 			PropertyEditorValueConvertersResolver.Current = new PropertyEditorValueConvertersResolver(
-				new []
-					{
-						typeof(DatePickerPropertyEditorValueConverter),
-						typeof(TinyMcePropertyEditorValueConverter),
-						typeof(YesNoPropertyEditorValueConverter)
-					});
+				PluginManager.Current.ResolvePropertyEditorValueConverters());
+			//add the internal ones, these are not public currently so need to add them manually
+			PropertyEditorValueConvertersResolver.Current.AddType<DatePickerPropertyEditorValueConverter>();
+			PropertyEditorValueConvertersResolver.Current.AddType<TinyMcePropertyEditorValueConverter>();
+			PropertyEditorValueConvertersResolver.Current.AddType<YesNoPropertyEditorValueConverter>();
 		}
 	}
 }

src/Umbraco.Core/PluginManager.cs

@@ -6,6 +6,7 @@ using System.Reflection;
 using System.Text;
 using System.Threading;
 using Umbraco.Core.Logging;
+using Umbraco.Core.PropertyEditors;
 using umbraco.interfaces;
 
 namespace Umbraco.Core
@@ -67,6 +68,15 @@ namespace Umbraco.Core
 			return ResolveTypes<ICacheRefresher>();
 		}
 
+		/// <summary>
+		/// Returns all available IPropertyEditorValueConverter
+		/// </summary>
+		/// <returns></returns>
+		internal IEnumerable<Type> ResolvePropertyEditorValueConverters()
+		{
+			return ResolveTypes<IPropertyEditorValueConverter>();
+		} 
+
 		/// <summary>
 		/// Returns all available IDataType in application
 		/// </summary>