WCF:有没有办法删除ExtensionData字段？

public class CustomDataContractSerializer : DataContractSerializer
{
    public CustomDataContractSerializer(Type type) : base(type)
    {
        this.KnownTypes = new List<Type> { typeof(MyType) };
    }
}

CustomDataContractSerializer serializer = new CustomDataContractSerializer(typeof(MyType));
MyType myType = new MyType();
using (MemoryStream ms = new MemoryStream())
{
    serializer.WriteObject(ms, myType);
    ms.Position = 0;
    MyType deserializedMyType = (MyType)serializer.ReadObject(ms);
}