public override async Task OnBeforeSendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
await _clientState.EnsureAuthorizedAsync(cancellationToken);
request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", _clientState.AccessToken);
request.Headers.Add((string)"Ocp-Apim-Subscription-Key", (string)_config.SubscriptionKey);
}
