如何在C# MVC中从ADFS3.0端点获取Refresh_Token？

<configSections>
  <section name="system.identityModel" type="System.IdentityModel.Configuration.SystemIdentityModelSection, System.IdentityModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
</configSections>

<system.identityModel>
  <identityConfiguration>
    <audienceUris>
      <add value="https://your-app-url.com" />
    </audienceUris>
    <issuerNameRegistry type="System.IdentityModel.Tokens.ValidatingIssuerNameRegistry, System.IdentityModel.Tokens.ValidatingIssuerNameRegistry">
      <authority name="https://your-adfs-url/adfs/services/trust">
        <keys>
          <add thumbprint="your-adfs-thumbprint" />
        </keys>
        <validIssuers>
          <add name="https://your-adfs-url/adfs/services/trust" />
        </validIssuers>
      </authority>
    </issuerNameRegistry>
    <certificateValidation certificateValidationMode="None" />
    <securityTokenHandlers>
      <clear />
      <add type="System.IdentityModel.Tokens.Saml2.Saml2SecurityTokenHandler, System.IdentityModel.Tokens.Saml2, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
    </securityTokenHandlers>
  </identityConfiguration>
</system.identityModel>

using System.IdentityModel.Tokens;

public class HomeController : Controller
{
    public ActionResult Index()
    {
        string adfsUrl = "https://your-adfs-url/adfs";
        string clientId = "your-client-id";
        string redirectUri = "https://your-app-url.com/callback";
        string resource = "your-resource";

        string authorizationEndpoint = $"{adfsUrl}/oauth2/authorize";
        string tokenEndpoint = $"{adfsUrl}/oauth2/token";

        string code = Request.QueryString["code"];

        if (!string.IsNullOrEmpty(code))
        {
            TokenClient tokenClient = new TokenClient(tokenEndpoint, clientId, "your-client-secret");
            TokenResponse tokenResponse = tokenClient.RequestAuthorizationCodeAsync(code, redirectUri).Result;

            string refreshToken = tokenResponse.RefreshToken;
            // 在这里可以将Refresh Token保存到数据库或其他持久化存储中

            // 其他处理逻辑...

            return View();
        }
        else
        {
            string authorizationUrl = new RequestUrl(authorizationEndpoint)
                .CreateAuthorizeUrl(clientId, "code", redirectUri, responseMode: "form_post", resource: resource);

            return Redirect(authorizationUrl);
        }
    }
}