public MicrosoftGraphAPI(string connectionString)
        {
            AzureServiceTokenProvider azureServiceTokenProvider = new AzureServiceTokenProvider(connectionString);

            string microsoftGraphEndpoint = "https://graph.microsoft.com";
            var    token = azureServiceTokenProvider.GetAccessTokenAsync(microsoftGraphEndpoint).ConfigureAwait(false).GetAwaiter().GetResult();

            Task authenticationDelegate(System.Net.Http.HttpRequestMessage req)
            {
                req.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
                return(Task.CompletedTask);
            }

            _restClient  = new RESTClient(token);
            _graphClient = new GraphServiceClient(new DelegateAuthenticationProvider(authenticationDelegate));
            _oneDrive    = new OneDrive(_restClient);
        }
 public OneDrive(RESTClient restClient)
 {
     _restClient = restClient;
 }