@JsonIgnore
    protected boolean isRefreshTokenExpired(final Ticket ticketState) {
        if (ticketState == null) {
            return true;
        }
        val expiringTime = toMaximumExpirationTime(ticketState);
        val now = ZonedDateTime.now(ZoneOffset.UTC);
        val result = expiringTime.isBefore(now);
        if (result) {
            LOGGER.trace("Ticket [{}] is expired because its expiration time [{}] is before [{}]",
                ticketState.getId(), expiringTime, now);
        }
        return result;
    }
Is refresh token expired ?

@param ticketState the ticket state
@return true/false
support/cas-server-support-oauth-core-api/src/main/java/org/apereo/cas/ticket/refreshtoken/OAuth20RefreshTokenExpirationPolicy.java