@Override
    public boolean isExpired(final TicketGrantingTicketAwareTicket ticketState) {
        return isRefreshTokenExpired(ticketState);
    }
An expiration policy that is independent from the parent ticket-granting ticket.
Activated when refresh tokens are expected to live beyond the normal expiration policy
of the {@code TGT} that lent a hand in issuing them. If the refresh token is considered expired
by this policy, the parent ticket's expiration policy is not consulted, making the RT independent.
@author Misagh Moayyed
@since 7.0.0
support/cas-server-support-oauth-core-api/src/main/java/org/apereo/cas/ticket/refreshtoken/OAuth20RefreshTokenStandaloneExpirationPolicy.java