找不到AuthorizationServerProvider和RefreshTokenProvider

Question

我正在尝试学习Owin令牌。在实现过程中，我正在使用AuthorizationServerProvider（）和RefreshTokenProvider（），并包含了命名空间Microsoft.Owin.Security.OAuth。但是却出现此参考错误。

using System;
using System.Threading.Tasks;
using System.Web.Http;
using Microsoft.Owin;
using Microsoft.Owin.Security.OAuth;
using Microsoft.Owin.Security.Infrastructure;
using Owin;

[assembly: OwinStartup(typeof(EgApi.App_Start.Startup))]

namespace EgApi.App_Start
{
    public class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            app.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);
            var myProvider = new **AuthorizationServerProvider()**;
            OAuthAuthorizationServerOptions options = new OAuthAuthorizationServerOptions
            {
                AllowInsecureHttp = true,
                TokenEndpointPath = new PathString("/token"),
                AccessTokenExpireTimeSpan = TimeSpan.FromMinutes(60),
                Provider = myProvider,
                RefreshTokenProvider = new **RefreshTokenProvider()**
            };
            app.UseOAuthAuthorizationServer(options);
            app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions());

            HttpConfiguration config = new HttpConfiguration();
            WebApiConfig.Register(config);
        }
    }
}