Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/System/Activities/RequiredArgumentAttribute.cs

@@ -0,0 +1,26 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace System.Activities
+{
+    using System;
+    using System.Runtime;
+
+    [AttributeUsage(AttributeTargets.Property)]
+    public sealed class RequiredArgumentAttribute : Attribute
+    {
+        public RequiredArgumentAttribute()
+            : base()
+        {
+        }
+
+        public override object TypeId
+        {
+            get
+            {
+                return this;
+            }
+        }
+    }
+}