fix mention parentage

libraries/Microsoft.Bot.Schema/MentionEx.cs

@@ -0,0 +1,22 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for
+// license information.
+//
+
+namespace Microsoft.Bot.Schema
+{
+    using Newtonsoft.Json;
+    using System.Linq;
+
+    /// <summary>
+    /// Mention information (entity type: "mention")
+    /// </summary>
+    public partial class Mention : Entity
+    {
+
+        partial void CustomInit()
+        {
+            this.Type = "mention";
+        }
+    }
+}