using System;

public class Program

{

    public static void Main()

    {

       IName p = new Person {Age = 4, Name = "Waldo"};

       var s1 = System.Text.Json.JsonSerializer.Serialize(p, p.GetType()); // --> {"Name":"Waldo"}

        Console.WriteLine(s1);

    }

}

​

public interface IName

{

    string Name { get; set; }

​

}

​

public class Person : IName

{

    public string Name { get; set; }

    public int Age { get; set; }

}

​