Added grouping functionality and tests.

IntegrationTests/Infrastructure/Child.cs

@@ -0,0 +1,14 @@
+namespace IntegrationTests.Infrastructure
+{
+    public class Child
+    {
+        public Child(string type, string value)
+        {
+            Type = type;
+            Value = value;
+        }
+
+        public string Type { get; set; }
+        public string Value { get; set; }
+    }
+}