Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

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

@@ -0,0 +1,37 @@
+//------------------------------------------------------------------------------
+// <copyright file="SettingsProviderCollection.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//------------------------------------------------------------------------------
+
+namespace System.Configuration {
+    using  System.Collections.Specialized;
+    using  System.Runtime.Serialization;
+    using  System.Configuration.Provider;
+
+   ////////////////////////////////////////////////////////////
+   ////////////////////////////////////////////////////////////
+   ////////////////////////////////////////////////////////////
+   public class SettingsProviderCollection : ProviderCollection
+   {
+       public override void Add(ProviderBase provider) {
+           if( provider == null )
+           {
+               throw new ArgumentNullException( "provider" );
+           }
+
+           if( !( provider is SettingsProvider ) )
+           {
+                throw new ArgumentException(SR.GetString(SR.Config_provider_must_implement_type, typeof(SettingsProvider).ToString()), "provider");
+           }
+ 
+           base.Add( provider );
+       }
+
+       new public SettingsProvider this[string name] {
+           get {
+               return (SettingsProvider) base[name];
+           }
+       }
+   }
+}