using System;

using System.Collections.Generic;

using Newtonsoft.Json;

using System.ComponentModel;

using System.Globalization;

​

using Employee = Response.Employee;

using Car = Response.Car;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        Response res = new Response { Dictionary = new Dictionary<Employee, List<Car>>()};

​

        Employee firstEmployee = new Employee {Name = "John Doe", Id ="1111", Seniority = 2};

        Employee secondEmployee = new Employee {Name = "Jane Doe", Id = "9999", Seniority = 10};

        res.Dictionary.Add(

            firstEmployee, 

            new List<Car>{ 

                new Car {OwnerId = "1111", Model = "Chevrolet Spark", RegistrationPlate = "LTO1234"},

                new Car {OwnerId = "1111", Model = "Chevrolet Malibu", RegistrationPlate = "LTO5678"}

            });

        res.Dictionary.Add(

            secondEmployee, 

            new List<Car>{ 

                new Car {OwnerId = "9999", Model = "Mercedes Benz", RegistrationPlate = "ABC1234"},

                new Car {OwnerId = "9999", Model = "Mercedes Maybach", RegistrationPlate = "ABC5678"}

            }); 

        var result = JsonConvert.SerializeObject(res);

        Console.WriteLine(result);

    }

}

​

public class Response

{

    public Dictionary<Employee, List<Car>> Dictionary { get; set; }

​

    public class Employee : TypeConverter

    {

        public string Name { get; set; }

        public string Id { get; set; }

        public decimal Seniority { get; set; }

        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)

        {

            if (sourceType == typeof(string))

            {

                return true;

            }

            return base.CanConvertFrom(context, sourceType);

        }

        public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)

        {

            if (destinationType == typeof(string))

            {

                return ((Employee)value).Name + "," + ((Employee)value).Id + "," + ((Employee)value).Seniority;

            }

            return base.ConvertTo(context, culture, value, destinationType);

        }

    }

​

    public class Car

    {

        public string OwnerId { get; set; }

        public string Model { get; set; }

        public string RegistrationPlate { get; set; }

    }

}

​