using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Serialization;

​

public class Program

{

    public class Test01

    {

        public string Test01PropertyNameOne { get; set; }

        public int Test01PropertyNameTwo { get; set; }

    }

    public class Test02

    {

        [JsonProperty(PropertyName = "test02_property_name_one")]

        public string Test02PropertyNameOne { get; set; }

        [JsonProperty(PropertyName = "test02_property_name_two")]

        public int Test02PropertyNameTwo { get; set; }

    }

    public static void Main()

    {

        var settings = new JsonSerializerSettings

        {

            ContractResolver = new DefaultContractResolver

            {

                NamingStrategy = new SnakeCaseNamingStrategy(),

            }

        };

​

        Console.WriteLine(JsonConvert.SerializeObject(

            new Test01

            {

                Test01PropertyNameOne = "123",

                Test01PropertyNameTwo = 123,

            }, Formatting.Indented, settings));

        Console.WriteLine(JsonConvert.SerializeObject(

            new Test02

            {

                Test02PropertyNameOne = "123",

                Test02PropertyNameTwo = 123,

            }, Formatting.Indented));

    }

}