如何获取 dotnet core 3 的路由属性？

我已将 dotnet core 2.2 升级到 3.preview 7。
所以在那之后，我无法获得自定义属性。
context.Resource在 2.2 版本中是类型AuthorizationFilterContext，但在版本 3 中是类型Microsoft.AspNetCore.Http.Endpoint.

现在我无法从端点获取属性。

using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc.Controllers;
using Microsoft.AspNetCore.Mvc.Filters;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Threading.Tasks;

namespace Gamma.Core.Security
{
    public abstract class AttributeAuthorizationHandler<TRequirement,     TAttribute>
    : AuthorizationHandler<TRequirement> where TRequirement
    : IAuthorizationRequirement where TAttribute : Attribute
    {
        Microsoft.AspNetCore.Http.IHttpContextAccessor _httpContextAccessor = null;
        public AttributeAuthorizationHandler(Microsoft.AspNetCore.Http.IHttpContextAccessor httpContextAccessor)
        {
            _httpContextAccessor = httpContextAccessor;
        }
        protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, TRequirement requirement)
        {
            var attributes = new List<TAttribute>();

            var action = (context.Resource as AuthorizationFilterContext)?.ActionDescriptor as ControllerActionDescriptor;
            if (context.Resource is Microsoft.AspNetCore.Http.Endpoint endpoint)
            {
                //endpoint.
            }

            if (action != null)
            {
                attributes.AddRange(GetAttributes(action.MethodInfo));
            }

            return HandleRequirementAsync(context, requirement, attributes);
        }

        protected abstract Task HandleRequirementAsync(AuthorizationHandlerContext context, TRequirement requirement, IEnumerable<TAttribute> attributes);

        private static IEnumerable<TAttribute> GetAttributes(MemberInfo memberInfo)
        {
            return memberInfo.GetCustomAttributes(typeof(TAttribute), false).Cast<TAttribute>();
        }
    }
}

我能够从 .NET Core 3.1 获取自定义属性AuthorizationHandlerContext using ControllerActionDescriptor in 布莱恩的回答 https://stackoverflow.com/a/58504298/12858798.

private IEnumerable<TAttribute> GetAttributes<TAttribute>(AuthorizationHandlerContext authContext)
{
    if (authContext.Resource is RouteEndpoint routeEndpoint)
    {
        var actionDescriptor = routeEndpoint.Metadata.OfType<ControllerActionDescriptor>().SingleOrDefault();
        var attributes = actionDescriptor?.MethodInfo.GetCustomAttributes(typeof(TAttribute), false).Cast<TAttribute>();
        return attributes;
    }
    
    return null;
}