1 files changed, 17 insertions, 2 deletions
diff --git a/csharp/ProtocolBuffers/GeneratedSingleExtension.cs b/csharp/ProtocolBuffers/GeneratedSingleExtension.cs
index d9a0adcf..55450f21 100644
--- a/csharp/ProtocolBuffers/GeneratedSingleExtension.cs
+++ b/csharp/ProtocolBuffers/GeneratedSingleExtension.cs
@@ -1,4 +1,19 @@
-using System;
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.
+// http://code.google.com/p/protobuf/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+using System;
 using Google.ProtocolBuffers.Descriptors;
 
 namespace Google.ProtocolBuffers {
@@ -6,7 +21,7 @@ namespace Google.ProtocolBuffers {
   /// <summary>
   /// Generated extension for a singular field.
   /// </remarks>
-  public class GeneratedSingleExtension<TExtension> : GeneratedExtensionBase<TExtension>  {
+  public sealed class GeneratedSingleExtension<TExtension> : GeneratedExtensionBase<TExtension>  {
     internal GeneratedSingleExtension(FieldDescriptor descriptor) : base(descriptor, typeof(TExtension)) {
     }