public static string AcquireAccessCode(AuthenticationContext context, string resource, string clientId, Uri redirectUri, UserIdentifier userId)
{
var handler = new AcquireTokenInteractiveHandler(context.Authenticator, context.TokenCache, resource, clientId, redirectUri, PromptBehavior.Auto, userId, null,
context.CreateWebAuthenticationDialog(PromptBehavior.Auto), true);
handler.CallState = null;
context.Authenticator.AuthorizationUri = context.Authority + "oauth2/authorize";
handler.AcquireAuthorization();
return(handler.authorizationResult.Code);
}