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diff --git a/csharp/src/Google.Protobuf/IMessage.cs b/csharp/src/Google.Protobuf/IMessage.cs
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+#region Copyright notice and license

+// Protocol Buffers - Google's data interchange format

+// Copyright 2008 Google Inc.  All rights reserved.

+// https://developers.google.com/protocol-buffers/

+//

+// Redistribution and use in source and binary forms, with or without

+// modification, are permitted provided that the following conditions are

+// met:

+//

+//     * Redistributions of source code must retain the above copyright

+// notice, this list of conditions and the following disclaimer.

+//     * Redistributions in binary form must reproduce the above

+// copyright notice, this list of conditions and the following disclaimer

+// in the documentation and/or other materials provided with the

+// distribution.

+//     * Neither the name of Google Inc. nor the names of its

+// contributors may be used to endorse or promote products derived from

+// this software without specific prior written permission.

+//

+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

+#endregion

+

+using System;

+using Google.Protobuf.Reflection;

+

+namespace Google.Protobuf

+{

+    /// <summary>

+    /// Interface for a Protocol Buffers message, supporting

+    /// basic operations required for serialization.

+    /// </summary>

+    public interface IMessage

+    {

+        /// <summary>

+        /// Merges the data from the specified coded input stream with the current message.

+        /// </summary>

+        /// <remarks>See the user guide for precise merge semantics.</remarks>

+        /// <param name="input"></param>

+        void MergeFrom(CodedInputStream input);

+

+        /// <summary>

+        /// Writes the data to the given coded output stream.

+        /// </summary>

+        /// <param name="output">Coded output stream to write the data to. Must not be null.</param>

+        void WriteTo(CodedOutputStream output);

+

+        /// <summary>

+        /// Calculates the size of this message in Protocol Buffer wire format, in bytes.

+        /// </summary>

+        /// <returns>The number of bytes required to write this message

+        /// to a coded output stream.</returns>

+        int CalculateSize();

+

+        /// <summary>

+        /// Descriptor for this message. All instances are expected to return the same descriptor,

+        /// and for generated types this will be an explicitly-implemented member, returning the

+        /// same value as the static property declared on the type.

+        /// </summary>

+        MessageDescriptor Descriptor { get; }

+    }

+

+    /// <summary>

+    /// Generic interface for a Protocol Buffers message,

+    /// where the type parameter is expected to be the same type as

+    /// the implementation class.

+    /// </summary>

+    /// <typeparam name="T">The message type.</typeparam>

+    public interface IMessage<T> : IMessage, IEquatable<T>, IDeepCloneable<T> where T : IMessage<T>

+    {

+        /// <summary>

+        /// Merges the given message into this one.

+        /// </summary>

+        /// <remarks>See the user guide for precise merge semantics.</remarks>

+        /// <param name="message">The message to merge with this one. Must not be null.</param>

+        void MergeFrom(T message);

+    }

+}