如何在web api发出响应前自定义json的datetime格式？

using Newtonsoft.Json;
using Newtonsoft.Json.Converters;
using Newtonsoft.Json.Serialization;
using System;
using System.Globalization;

public class CustomDateTimeConverter : IsoDateTimeConverter
{
    public CustomDateTimeConverter()
    {
        DateTimeFormat = "yyyy-MM-dd HH:mm:ss";
    }
}

public class CustomContractResolver : DefaultContractResolver
{
    protected override JsonContract CreateContract(Type objectType)
    {
        var contract = base.CreateContract(objectType);
        if (objectType == typeof(DateTime) || objectType == typeof(DateTime?))
        {
            contract.Converter = new CustomDateTimeConverter();
        }
        return contract;
    }
}

public class CustomJsonResult : JsonResult
{
    public CustomJsonResult(object value)
    {
        Value = value;
        SerializerSettings = new JsonSerializerSettings
        {
            ContractResolver = new CustomContractResolver(),
            Formatting = Formatting.Indented
        };
    }
}

// 在Controller中使用CustomJsonResult返回自定义JSON格式的响应
public IActionResult Get()
{
    var data = new
    {
        Id = 1,
        Name = "John",
        Birthday = DateTime.Now
    };

    return new CustomJsonResult(data);
}