Authorization Code Flow Error in ASP.Net Form using Owin Starup - owin

Question

We are implementing Azure SSO in Traditional ASP.Net Web Application and we want to implement Authorization Code Flow for generating Refresh, Access and Id Tokens.
We have implemented the below code in AuthorizationCodeReceived function of the owin's app.UseOpenIdConnectAuthentication class. From the below mentioned code we are able to successfully fetch the Refreshtoken, AccessToken and IdToken.
But notification.AuthenticationTicket is null and it throws null reference excpetion so we are not able to add the claims for id and access tokens.
Also in the aspx.cs file the HttpContext.Current.User.Identity.IsAuthenticated is returned as false even after generating all the 3 tokens.
Please suggest why notification.AuthenticationTicket is null inside AuthorizationCodeReceived event and what changes we have to do inside AuthorizationCodeReceived event to make HttpContext.Current.User.Identity.IsAuthenticated as "true".
app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType);
app.UseKentorOwinCookieSaver();
app.UseCookieAuthentication(new CookieAuthenticationOptions());
Microsoft.IdentityModel.Protocols.OpenIdConnect.OpenIdConnectProtocolValidator dd = new Microsoft.IdentityModel.Protocols.OpenIdConnect.OpenIdConnectProtocolValidator();
dd.RequireNonce = false;
app.UseOpenIdConnectAuthentication(
new OpenIdConnectAuthenticationOptions
{
ClientId = clientId,
Authority = authority,
ClientSecret = clientSecret,
PostLogoutRedirectUri = redirectUri,
RedirectUri = redirectUri,
Scope = "openid profile email offline_access",
ResponseType = OpenIdConnectResponseType.Code,
SignInAsAuthenticationType = "Cookies",
Notifications = new OpenIdConnectAuthenticationNotifications()
{
AuthenticationFailed = (context) =>
{
return System.Threading.Tasks.Task.FromResult(0);
},
AuthorizationCodeReceived = async notification =>
{
using (var client = new HttpClient())
{
var configuration = await notification.Options.ConfigurationManager.GetConfigurationAsync(notification.Request.CallCancelled);
var request = new HttpRequestMessage(HttpMethod.Post, configuration.TokenEndpoint);
request.Content = new FormUrlEncodedContent(new Dictionary<string, string>
{
[OpenIdConnectParameterNames.ClientId] = notification.Options.ClientId,
[OpenIdConnectParameterNames.ClientSecret] = notification.Options.ClientSecret,
[OpenIdConnectParameterNames.Code] = notification.ProtocolMessage.Code,
[OpenIdConnectParameterNames.GrantType] = "authorization_code",
[OpenIdConnectParameterNames.RedirectUri] = notification.Options.RedirectUri
});
var response = await client.SendAsync(request, notification.Request.CallCancelled);
response.EnsureSuccessStatusCode();
var payload = JObject.Parse(await response.Content.ReadAsStringAsync());
notification.AuthenticationTicket.Identity.AddClaim(new Claim(
type: OpenIdConnectParameterNames.AccessToken,
value: payload.Value<string>(OpenIdConnectParameterNames.AccessToken)));
notification.AuthenticationTicket.Identity.AddClaim(new Claim(
type: OpenIdConnectParameterNames.IdToken,
value: payload.Value<string>(OpenIdConnectParameterNames.IdToken)));
}
},
// Attach the id_token stored in the authentication cookie to the logout request.
RedirectToIdentityProvider = notification =>
{
if (notification.ProtocolMessage.RequestType == OpenIdConnectRequestType.Logout)
{
var token = notification.OwinContext.Authentication.User?.FindFirst(OpenIdConnectParameterNames.IdToken);
if (token != null)
{
notification.ProtocolMessage.IdTokenHint = token.Value;
}
}
return Task.CompletedTask;
},
SecurityTokenValidated = (context) =>
{ if (context != null)
{
if (context.ProtocolMessage != null && !string.IsNullOrEmpty(context.ProtocolMessage.IdToken))
{
context.AuthenticationTicket.Identity.AddClaim(new Claim("IdToken", context.ProtocolMessage.IdToken));
}
}
return Task.FromResult(0);
}
}
}
);