Web API App-Only with Graph API

init-authenticationcontext.cs

public class OrganisationController : Controller
{
  ...

  public OrganisationController(IOptions<GraphApp> graphApp)
  {
    this._graphApp = graphApp.Value;
    this.Init();
  }

  ...
  
  private void Init()
  {
    var tenant = this._graphApp.Tenant;
    var authUrl = this._graphApp.AuthUrl;
    var authority = string.Format(authUrl, tenant);
  
    this._authContext = new AuthenticationContext(authority);
  
    var clientId = this._graphApp.ClientId;
    var clientSecret = this._graphApp.ClientSecret;
  
    this._credential = new ClientCredential(clientId, clientSecret);
  
    this._graphUrl = this._graphApp.GraphUrl;
    this._version = this._graphApp.Version;
  }
}