docs: public void start(@NonNull Activity activity, @NonNull AuthCallback callback, int permissionRequestCode, int authenticationRequestCode) {
          this.callback = callback;
          this.authenticationRequestCode = authenticationRequestCode;
  
          if (checkPermissions(activity)) {
              Log.v(TAG, "All permissions were already granted, the authentication flow is starting.");
              requestAuth(activity, authenticationRequestCode);
          } else {
              Log.d(TAG, "Some permissions were not previously granted, requesting them now.");
              requestPermissions(activity, permissionRequestCode);
          }
      }