@JsonIgnore
    @Override
    public ZonedDateTime toMaximumExpirationTime(final Ticket ticketState) {
        val creationTime = ticketState.getCreationTime();
        return creationTime.plusSeconds(this.timeToKillInSeconds);
    }
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