Atualizar o token em vb net

Private Function DoAuthentication(ByRef rStrToken As String, ByRef rParameters As OAuth2Parameters) As Boolean
    Dim credential As UserCredential
    Dim Secrets = New ClientSecrets() With {
        .ClientId = m_strClientID,
        .ClientSecret = m_strClientSecret
    }
    'm_Scopes.Add(CalendarService.Scope.Calendar)
    m_Scopes.Add("https://www.googleapis.com/auth/calendar https://www.google.com/m8/feeds/ https://mail.google.com/")

    Try
        credential = GoogleWebAuthorizationBroker.AuthorizeAsync(Secrets, m_Scopes,
                                                                 "user", CancellationToken.None,
                                                                 New FileDataStore("PublicTalkSoftware.Calendar.Application")).Result()

        ' Create the calendar service using an initializer instance
        Dim initializer As New BaseClientService.Initializer() With {
            .HttpClientInitializer = credential,
            .ApplicationName = "~~~~~~~~~~"
        }
        m_Service = New CalendarService(initializer)

        rStrToken = credential.Token.AccessToken.ToString()
        rParameters.AccessToken = credential.Token.AccessToken
        rParameters.RefreshToken = credential.Token.RefreshToken
    Catch ex As Exception
        ' We encountered some kind of problem, perhaps they have not yet authenticated?
        Return False
    End Try

    Return True
End Function
MF