Cleanup DI

src/Umbraco.Core/DI/CollectionBuilderBase.cs

@@ -54,11 +54,14 @@ namespace Umbraco.Core.DI
             var argType = typeof(IEnumerable<TItem>);
             var ctorArgTypes = new[] { argType };
             var constructor = typeof(TCollection).GetConstructor(ctorArgTypes);
-            if (constructor == null) throw new InvalidOperationException();
-            var exprArg = Expression.Parameter(argType, "items");
-            var exprNew = Expression.New(constructor, exprArg);
-            var expr = Expression.Lambda<Func<IEnumerable<TItem>, TCollection>>(exprNew, exprArg);
-            _collectionCtor = expr.Compile();
+            if (constructor != null)
+            {
+                var exprArg = Expression.Parameter(argType, "items");
+                var exprNew = Expression.New(constructor, exprArg);
+                var expr = Expression.Lambda<Func<IEnumerable<TItem>, TCollection>>(exprNew, exprArg);
+                _collectionCtor = expr.Compile();
+            }
+            // else _collectionCtor remains null, assuming CreateCollection has been overriden
 
             // we just don't want to support re-registering collections here
             var registration = Container.GetAvailableService<TCollection>();

src/Umbraco.Core/DI/LightInjectExtensions.cs

@@ -275,6 +275,12 @@ namespace Umbraco.Core.DI
             }, null);
         }
 
+        /// <summary>
+        /// Registers and instanciates a collection builder.
+        /// </summary>
+        /// <typeparam name="TBuilder">The type of the collection builder.</typeparam>
+        /// <param name="container">The container.</param>
+        /// <returns>The collection builder.</returns>
         public static TBuilder RegisterCollectionBuilder<TBuilder>(this IServiceContainer container)
         {
             // make sure it's not already registered