Updated TreeDefinitionCollection to use PluginTypeResolver and fixed its code to be thread safe.

Updated restExtensions to use PluginTypeResolver and added unit test for resolving these types.
Updated TypeFinder2 with a slight perf increase.

src/Umbraco.Web/PluginTypeResolverExtensions.cs

@@ -3,6 +3,8 @@ using System.Collections.Generic;
 using System.Threading;
 using Umbraco.Core;
 using Umbraco.Web.Routing;
+using umbraco.interfaces;
+using umbraco.presentation.umbracobase;
 
 
 namespace Umbraco.Web
@@ -12,16 +14,24 @@ namespace Umbraco.Web
 	/// </summary>
 	public static class PluginTypeResolverExtensions
 	{
+		/// <summary>
+		/// Returns all available ITrees in application
+		/// </summary>
+		/// <param name="resolver"></param>
+		/// <returns></returns>
+		internal static IEnumerable<Type> ResolveTrees(this PluginTypeResolver resolver)
+		{
+			return resolver.ResolveTypes<ITree>();
+		}
 
-		///// <summary>
-		///// Returns all IDocumentLookup types
-		///// </summary>
-		///// <param name="resolver"></param>
-		///// <returns></returns>
-		//internal static IEnumerable<Type> ResolveLookups(this PluginTypeResolver resolver)
-		//{
-		//    return resolver.ResolveTypes<IDocumentLookup>();
-		//}
-
+		/// <summary>
+		/// Returns all classes attributed with RestExtension attribute
+		/// </summary>
+		/// <param name="resolver"></param>
+		/// <returns></returns>
+		internal static IEnumerable<Type> ResolveRestExtensions(this PluginTypeResolver resolver)
+		{
+			return resolver.ResolveAttributedTypes<RestExtension>();
+		}
 	}
 }