1 files changed, 17 insertions, 4 deletions
diff --git a/csharp/ProtocolBuffers/Collections/ReadOnlyDictionary.cs b/csharp/ProtocolBuffers/Collections/ReadOnlyDictionary.cs
index b67d5cd3..cd4b1898 100644
--- a/csharp/ProtocolBuffers/Collections/ReadOnlyDictionary.cs
+++ b/csharp/ProtocolBuffers/Collections/ReadOnlyDictionary.cs
@@ -1,14 +1,27 @@
-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 System.Collections;
 using System.Collections.Generic;
-using System.Text;
-using IEnumerable=System.Collections.IEnumerable;
 
 namespace Google.ProtocolBuffers.Collections {
   /// <summary>
   /// Read-only wrapper around another dictionary.
   /// </summary>
-  public class ReadOnlyDictionary<TKey, TValue> : IDictionary<TKey, TValue> {
+  public sealed class ReadOnlyDictionary<TKey, TValue> : IDictionary<TKey, TValue> {
     readonly IDictionary<TKey, TValue> wrapped;
 
     public ReadOnlyDictionary(IDictionary<TKey, TValue> wrapped) {