authentication property
Retrieve IGoogleSignInAuthentication for this account.
shouldRecoverAuth sets whether to attempt to recover authentication if
user action is needed. If an attempt to recover authentication fails a
PlatformException is thrown with possible error code
kFailedToRecoverAuthError.
Otherwise, if shouldRecoverAuth is false and the authentication can be
recovered by user action a PlatformException is thrown with error code
kUserRecoverableAuthError.
Implementation
Future<IGoogleSignInAuthentication> authentication;