Renamed config interfaces properly with Section suffix, re-implemented the For<T> UmbracoConfiguration method to retreive specific settings... might use this entirely instead of the nested access as it might make it easier to mock.

src/Umbraco.Core/PluginManager.cs

@@ -8,6 +8,7 @@ using System.Text;
 using System.Threading;
 using System.Web.Compilation;
 using System.Xml.Linq;
+using Umbraco.Core.Configuration;
 using Umbraco.Core.IO;
 using Umbraco.Core.Logging;
 using Umbraco.Core.Models;
@@ -445,7 +446,18 @@ namespace Umbraco.Core
         }
 
         /// <summary>
-        /// Returns all classes attributed with XsltExtensionAttribute attribute
+        /// Returns all classes of type IUmbracoConfigurationSection
+        /// </summary>
+        /// <returns></returns>
+        internal IEnumerable<Type> ResolveUmbracoConfigurationSections()
+        {
+            //don't cache the result since it's a one time lookup for a type anyways
+            //ONLY look in the CORE assembly for performance.
+            return ResolveTypes<IUmbracoConfigurationSection>(false, new[] { typeof(IUmbracoConfigurationSection).Assembly });
+        }
+
+        /// <summary>
+        /// Returns all classes of type ICacheRefresher
         /// </summary>
         /// <returns></returns>
         internal IEnumerable<Type> ResolveCacheRefreshers()
@@ -729,10 +741,10 @@ namespace Umbraco.Core
         /// </summary>
         /// <typeparam name="T"></typeparam>
         /// <returns></returns>
-        internal IEnumerable<Type> ResolveTypes<T>(bool cacheResult = true)
+        internal IEnumerable<Type> ResolveTypes<T>(bool cacheResult = true, IEnumerable<Assembly> specificAssemblies = null)
         {
             return ResolveTypes<T>(
-                () => TypeFinder.FindClassesOfType<T>(AssembliesToScan),
+                () => TypeFinder.FindClassesOfType<T>(specificAssemblies ?? AssembliesToScan),
                 TypeResolutionKind.FindAllTypes,
                 cacheResult);
         }