问Dictionary<Key、Value>上.NET二进制序列化的奇怪行为

EN

[Serializable]
public class Data : IDeserializationCallback
{
    public List<string> List { get; set; }

    public Dictionary<string, string> Dictionary { get; set; }

    public Data()
    {
        Dictionary = new Dictionary<string, string> { { "hello", "hello" }, { "CU", "CU" } };
        List = new List<string> { "hello", "CU" };
    }

    public static Data Load(string filename)
    {
        using (Stream stream = File.OpenRead(filename))
        {
            Data result = (Data)new BinaryFormatter().Deserialize(stream);
            TestsLengthsOfDataStructures(result);

            return result;
        }
    }

    public void Save(string fileName)
    {
        using (Stream stream = File.Create(fileName))
        {
            new BinaryFormatter().Serialize(stream, this);
        }
    }

    public void OnDeserialization(object sender)
    {
        TestsLengthsOfDataStructures(this);
    }

    private static void TestsLengthsOfDataStructures(Data data)
    {
        Debug.Assert(data.List.Count == 2, "List");
        Debug.Assert(data.Dictionary.Count == 2, "Dictionary");
    }
}