@Override
    public ExpirationPolicy buildTicketExpirationPolicyFor(final RegisteredServiceDefinition registeredService) {
        if (registeredService instanceof final OAuthRegisteredService service && service.getRefreshTokenExpirationPolicy() != null) {
            val policy = service.getRefreshTokenExpirationPolicy();
            val timeToKill = policy.getTimeToKill();
            if (StringUtils.isNotBlank(timeToKill)) {
                val timeToKillInSeconds = Beans.newDuration(timeToKill).toSeconds();
                return buildExpirationPolicyFor(timeToKillInSeconds);
            }
        }
        return toTicketExpirationPolicy();
    }
To ticket expiration policy.

@return the expiration policy
support/cas-server-support-oauth-core-api/src/main/java/org/apereo/cas/ticket/refreshtoken/OAuth20RefreshTokenExpirationPolicyBuilder.java