public static string RegisterLoginContinuation(OIDCLoginContinuation continuation)
        {
            var key = Guid.NewGuid().ToString();

            _ContinuationMap.Add(key, continuation);
            return(key);
        }
        private static void OidcCallback(Uri loginUri, Uri redirectUri, OIDCLoginContinuation continuation)
        {
            Device.BeginInvokeOnMainThread(() =>
            {
                var continuationKey = RegisterLoginContinuation(continuation);
                var data            = new Dictionary <string, object> {
                    [OpenIDPage.LoginUrlKey]        = loginUri?.AbsoluteUri,
                    [OpenIDPage.RedirectUrlKey]     = redirectUri?.AbsoluteUri,
                    [OpenIDPage.ContinuationKeyKey] = continuationKey
                };
                var nextPage = new OpenIDPage {
                    BindingContext = data
                };

                App.Current.MainPage.Navigation.PushAsync(nextPage);
            });
        }