Mongo Bson Serialization of null Interface properties.

using System;
using System.Diagnostics;

using MongoDB.Bson;
using MongoDB.Bson.Serialization;
using MongoDB.Driver;

namespace ConsoleApplication2
{
    public interface IProp
    {
        string AString { get; set; }
    }

    public class PropImpl:IProp
    {
        public string AString { get; set; }
    }

    public class SuperClass
    {
        public string Name { get; set; }
        public IProp AProp { get; set; }
    }

    class Program
    {
        private static MongoServer server = MongoServer.Create("mongodb://localhost/?safe=true");
        private static MongoDatabase db = server["InterfaceTest"];
        static void Main()
        {
            var superClass1 = new SuperClass
                {
                    Name = Guid.NewGuid().ToString(),
                    AProp = new PropImpl()
                };
            var superClass2 = new SuperClass
            {
                Name = Guid.NewGuid().ToString()
            };
            BsonSerializer.LookupSerializer(typeof(PropImpl));
            Debug.Print("superClass1: {0}", superClass1.ToJson());
            Debug.Print("superClass2: {0}", superClass2.ToJson());
            //var collection = db["PropA"].Insert(superClass);
        }
    }
}