void addNestedMessage(Message message)
    {
        if (nestedMessages.put(message.name, message) != null)
        {
            throw err("Duplicate nested message: " +
                    message.name + " from message: " + name, getProto());
        }
    }
Represents the message defined in the {@link Proto}.

@author David Yu
@created Dec 19, 2009
protostuff-parser/src/main/java/io/protostuff/parser/Message.java