#nullable enable

using System;

using System.Text.Json;

public class Program

{

    public static void Main()

    {

        var deserialised = JsonSerializer.Deserialize<TestClass>("{ \"Name\": \"Aleb\", \"Age\": 4 }");

        Console.WriteLine("Hello World");

        Console.WriteLine(deserialised!.Name);

        Console.WriteLine(deserialised!.Age);

        JsonSerializerOptions options = new JsonSerializerOptions();        

        options.DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull;

        var serialized = JsonSerializer.Serialize(deserialised, options);

        Console.WriteLine(serialized);

    }

}

​

#nullable enable

public class TestClass

{

    public string? Name {get;set;}

    public int? Age {get;set;}

}