在将JSON反序列化为C#对象时，如何映射动态字段名？

using Newtonsoft.Json;
using System.Collections.Generic;

public class MyObject
{
    public string Name { get; set; }
    
    [JsonExtensionData]
    private Dictionary<string, object> _additionalData;
    
    public T GetAdditionalData<T>(string fieldName)
    {
        if (_additionalData != null && _additionalData.ContainsKey(fieldName))
        {
            return (T)_additionalData[fieldName];
        }
        return default(T);
    }
}

// 反序列化JSON并映射动态字段名
string json = "{\"Name\":\"John\",\"Age\":30,\"City\":\"New York\"}";
MyObject obj = JsonConvert.DeserializeObject<MyObject>(json);

// 访问动态字段名
string city = obj.GetAdditionalData<string>("City");
int age = obj.GetAdditionalData<int>("Age");

Console.WriteLine($"Name: {obj.Name}");
Console.WriteLine($"City: {city}");
Console.WriteLine($"Age: {age}");