Imported Upstream version 5.14.0.78

Former-commit-id: 3494343bcc9ddb42b36b82dd9ae7b69e85e0229f

mcs/class/System.Runtime.Serialization/ReferenceSources/NotImplemented.cs

@@ -0,0 +1,32 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace System
+{
+    //
+    // This class enables one to throw a NotImplementedException using the following idiom:
+    //
+    //     throw NotImplemented.ByDesign;
+    //
+    // Used by methods whose intended implementation is to throw a NotImplementedException (typically
+    // virtual methods in public abstract classes that intended to be subclassed by third parties.)
+    //
+    // This makes it distinguishable both from human eyes and CCI from NYI's that truly represent undone work.
+    //
+    internal static class NotImplemented
+    {
+        internal static Exception ByDesign
+        {
+            get
+            {
+                return new NotImplementedException();
+            }
+        }
+
+        internal static Exception ByDesignWithMessage(String message)
+        {
+            return new NotImplementedException(message);
+        }
+    }
+}