Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.IdentityModel/System/IdentityModel/OpenObject.cs

@@ -0,0 +1,24 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+
+namespace System.IdentityModel
+{
+    using System.Collections.Generic;
+
+    /// <summary>
+    /// An abstract class that provides a generic property bag to derived classes.
+    /// </summary>
+    public abstract class OpenObject
+    {
+        Dictionary<string, object> _properties = new Dictionary<string, object>(); // for any custom data
+
+        /// <summary>
+        /// Gets the properties bag to extend object.
+        /// </summary>
+        public Dictionary<string, object> Properties
+        {
+            get { return _properties; }
+        }
+    }
+}