如何在将JSON解析为JToken时将所有空字符串更改为null

using Newtonsoft.Json;
using Newtonsoft.Json.Linq;

public class JsonHelper
{
    public static JToken ParseJson(string jsonString)
    {
        JToken jToken = JToken.Parse(jsonString);
        ConvertEmptyStringToNull(jToken);
        return jToken;
    }

    private static void ConvertEmptyStringToNull(JToken jToken)
    {
        if (jToken.Type == JTokenType.Object)
        {
            foreach (JProperty property in jToken.Children<JProperty>())
            {
                if (property.Value.Type == JTokenType.String && property.Value.ToString() == "")
                {
                    property.Value = JValue.CreateNull();
                }
                else
                {
                    ConvertEmptyStringToNull(property.Value);
                }
            }
        }
        else if (jToken.Type == JTokenType.Array)
        {
            foreach (JToken child in jToken.Children())
            {
                ConvertEmptyStringToNull(child);
            }
        }
    }
}

string jsonString = "{\"name\":\"John\",\"age\":\"\",\"address\":{\"street\":\"\",\"city\":\"New York\"}}";
JToken jToken = JsonHelper.ParseJson(jsonString);
Console.WriteLine(jToken.ToString());

{
  "name": "John",
  "age": null,
  "address": {
    "street": null,
    "city": "New York"
  }
}