How to serialize only SOME properties of an object JSON.NET

using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace showcase_json.net_filtering_serialization
{
    class serializationTestClass {
        public int testPropOne { get; set; }
        public DateTime testPropTwo { get; set; }
        public string testPropThree { get; set; }

    }

    class Program
    {
        static void Main(string[] args)
        {
            var testIntance = new serializationTestClass() { testPropOne = 28, testPropTwo = DateTime.Now, testPropThree = "hello world" };
            var settings = new JsonSerializerSettings() { ContractResolver = new CriteriaContractResolver<serializationTestClass>(new List<string>() { "testPropTwo", "testPropThree" }) };
            var serialized = JsonConvert.SerializeObject(testIntance, settings);
            Console.WriteLine(serialized);
            Console.ReadKey();
        }
    }

    //<summary>
    //json.net serializes ALL properties of a class by default
    //this class will tell json.net to only serialize properties if
    //they MATCH the list of valid columns passed through the querystring to criteria object
    //</summary>
    public class CriteriaContractResolver<T> : DefaultContractResolver
    {
        List<string> _properties;

        public CriteriaContractResolver(List<string> properties)
        {
            _properties = properties;
        }

        protected override IList<JsonProperty> CreateProperties(Type cType, MemberSerialization memberSerialization)
        {
            IList<JsonProperty> filtered = new List<JsonProperty>();

            foreach (JsonProperty p in base.CreateProperties(cType, memberSerialization))    //fix this problem
            {
                if (_properties.Contains(p.PropertyName))
                    filtered.Add(p);

            }
            return filtered;

        }
    }
}