Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System/sys/system/configuration/ReadOnlyNameValueCollection.cs

@@ -0,0 +1,26 @@
+//------------------------------------------------------------------------------
+// <copyright file="ReadOnlyNameValueCollection.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Configuration {
+    using System.Collections;
+    using System.Collections.Specialized;
+
+    /// <devdoc>
+    ///    <para>[To be supplied.]</para>
+    /// </devdoc>
+    internal class ReadOnlyNameValueCollection : NameValueCollection {
+
+        internal ReadOnlyNameValueCollection(IEqualityComparer equalityComparer) : base(equalityComparer) {
+        }
+
+        internal ReadOnlyNameValueCollection(ReadOnlyNameValueCollection value) : base(value) {
+        }
+
+        internal void SetReadOnly() {
+            IsReadOnly = true;
+        }
+    }
+}