'TRUE' if the certificate associated with a CertificateManager instance is expired.
A certificate is expired if any of the following conditions hold: 1) the current time is before or after the
certificate validity dates, 2) the certificate is not valid according to a trusted Certificate Authority, or
3) no certificate can be found.
1 2 3 4
a CertificateManager instance
(Not yet used)
TRUE if the certificate is expired