Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.ServiceModel/System/ServiceModel/MessageHeaderAttribute.cs

@@ -0,0 +1,43 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+namespace System.ServiceModel
+{
+    [AttributeUsage(ServiceModelAttributeTargets.MessageMember, AllowMultiple = false, Inherited = false)]
+    public class MessageHeaderAttribute : MessageContractMemberAttribute
+    {
+        bool mustUnderstand;
+        bool isMustUnderstandSet;
+        bool relay;
+        bool isRelaySet;
+        string actor;
+
+        public bool MustUnderstand
+        {
+            get { return mustUnderstand; }
+            set { mustUnderstand = value; isMustUnderstandSet = true; }
+        }
+
+        public bool Relay
+        {
+            get { return relay; }
+            set { relay = value; isRelaySet = true; }
+        }
+
+        public string Actor
+        {
+            get { return actor; }
+            set { actor = value; }
+        }
+
+        internal bool IsMustUnderstandSet
+        {
+            get { return isMustUnderstandSet; }
+        }
+
+        internal bool IsRelaySet
+        {
+            get { return isRelaySet; }
+        }
+    }
+}