public async Task <string> PasswordVaultLoginAsync()
        {
            PasswordCredential passwordCredential = settings.GetPasswordCredential();

            if (passwordCredential != null)
            {
                HttpResult <AccessTokenResponse> result;
                using (AccountClient accountClient = ClientFactory.CreateAccountClient())
                {
                    result = await accountClient.LoginAsync(passwordCredential.UserName, passwordCredential.Password);
                }
                if (result.Succeeded)
                {
                    return(result.Content.AccessToken);
                }
                settings.ClearPasswordCredentials();
            }
            return(null);
        }