using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        var obj1 = new A(4, true);

        var obj2 = new B("hello world");

        var json1 = JObject.FromObject(obj1);

        var json2 = JObject.FromObject(obj2);

        json1.Merge(json2);

        Console.WriteLine(json1.ToString());

    }

}

​

public class A

{

    public A(int x, bool y)

    {

        X = x;

        Y = y;

    }

​

    [JsonProperty("x_thing")]

    public int X { get; }

​

    [JsonProperty("y_thing")]

    public bool Y { get; }

}

​

public class B

{

    public B(string s)

    {

        S = s;

    }

​

    [JsonProperty("string_thing")]

    public string S { get; }

}