using System;

using Newtonsoft.Json;

public class Program

{

    public class MyDto

    {

        public int RequiredProperty {get;set;}

    }

    public static void Main()

    {

        var dto = JsonConvert.DeserializeObject<MyDto>("{ 'RequiredProperty': null }",  new JsonSerializerSettings { NullValueHandling = NullValueHandling.Include });

        Console.WriteLine(dto.RequiredProperty);

    }

}

​