@Override
        public boolean isExpired(final TicketGrantingTicketAwareTicket ticketState) {
            return isAccessTokenExpired(ticketState);
        }
An expiration policy that is independent from the parent ticket-granting ticket.
Activated when access tokens are expected to live beyond the normal expiration policy
of the TGT that lent a hand in issuing them. If the access token is considered expired
by this policy, the parent ticket's expiration policy is not consulted, making the AT independent.
support/cas-server-support-oauth-core-api/src/main/java/org/apereo/cas/ticket/accesstoken/OAuth20AccessTokenExpirationPolicy.java