Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.IdentityModel/System/IdentityModel/Selectors/AudienceUriMode.cs

@@ -0,0 +1,35 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace System.IdentityModel.Selectors
+{
+    using System.ComponentModel;
+
+    public enum AudienceUriMode
+    {
+        Never,
+        Always,
+        BearerKeyOnly
+    }
+
+    public static class AudienceUriModeValidationHelper
+    {
+        public static bool IsDefined(AudienceUriMode validationMode)
+        {
+            return validationMode == AudienceUriMode.Never
+                || validationMode == AudienceUriMode.Always
+                || validationMode == AudienceUriMode.BearerKeyOnly;
+        }
+
+        internal static void Validate(AudienceUriMode value)
+        {
+            if (!IsDefined(value))
+            {
+                throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidEnumArgumentException("value", (int)value,
+                    typeof(AudienceUriMode)));
+            }
+        }
+
+    }
+}