using System;

using System.Collections.Generic;

using System.Linq;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        string json = @"

            {

              ""Standards"": {

                ""Alpha"":""Alpha"",

                ""Beta"":""Beta"",

                ""Gamma"":""Gamma""

              }

            }";

        Model model = JsonConvert.DeserializeObject<Model>(json);

        Console.WriteLine(string.Join(", ", model.Standards));

        Console.WriteLine();

        json = JsonConvert.SerializeObject(model, Formatting.Indented);

        Console.WriteLine(json);

​

    }

}

​

public class Model

{

    [JsonConverter(typeof(CustomHashSetConverter))]

    public HashSet<string> Standards { get; set; }

}

​

public class CustomHashSetConverter : JsonConverter

{

    public override bool CanConvert(Type objectType)

    {

        return objectType == typeof(HashSet<string>);

    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)

    {

        JObject jo = JObject.Load(reader);

        return new HashSet<string>(jo.Properties().Select(p => p.Name));

    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)

        {

            HashSet<string> hashSet = (HashSet<string>)value;

            JArray ja = new JArray(hashSet);

            ja.WriteTo(writer);

        }

}

​