code: function OAuth2Client(callContext, authority) {
    this._tokenEndpoint = authority.tokenEndpoint;
    this._deviceCodeEndpoint = authority.deviceCodeEndpoint;
  
    this._log = new Logger('OAuth2Client', callContext._logContext);
    this._callContext = callContext;
    this._cancelPollingRequest = false;
  }
docs: Constructs an instances of OAuth2Client
  @constructor
  @private
  @param {object} callContext Contains any context information that applies to the request.
  @param {string|url} authority  An url that points to an authority.