using System;

using Newtonsoft.Json;

public class Program

{

    public class Telemetry

    {

        [JsonProperty("payload", NullValueHandling = NullValueHandling.Ignore)]

        public string Payload { get; set; }

        [JsonProperty("dup", DefaultValueHandling = DefaultValueHandling.Ignore)]

        public bool IsDuplicated { get; set; }

    }

    public static void Main()

    {

        Print(new Telemetry() { Payload = "1", IsDuplicated = false });

        Print(new Telemetry() { Payload = "1", IsDuplicated = true });

        Print(new Telemetry() { IsDuplicated = false });

        Print(new Telemetry() { IsDuplicated = true });

    }

    static void Print(object obj)

    {

        Console.WriteLine(JsonConvert.SerializeObject(obj));

    }

}