如何将ExpandoObject的字典设置为不区分大小写？

using System;
using System.Dynamic;

public class CaseInsensitiveExpandoObject : DynamicObject
{
    private readonly ExpandoObject _expandoObject = new ExpandoObject();
    private readonly Dictionary<string, string> _keyMapping = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);

    public override bool TrySetMember(SetMemberBinder binder, object value)
    {
        string key = binder.Name;
        _keyMapping[key] = binder.Name;
        ((IDictionary<string, object>)_expandoObject)[key] = value;
        return true;
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        string key = binder.Name;
        if (_keyMapping.TryGetValue(key, out string actualKey))
        {
            return ((IDictionary<string, object>)_expandoObject).TryGetValue(actualKey, out result);
        }
        else
        {
            result = null;
            return false;
        }
    }
}

dynamic caseInsensitiveExpandoObject = new CaseInsensitiveExpandoObject();
caseInsensitiveExpandoObject.Name = "John";
caseInsensitiveExpandoObject.Age = 30;

Console.WriteLine(caseInsensitiveExpandoObject.Name); // 输出 "John"
Console.WriteLine(caseInsensitiveExpandoObject.name); // 输出 "John"
Console.WriteLine(caseInsensitiveExpandoObject.AGE); // 输出 "John"