public ExpirationPolicy toTicketExpirationPolicy() {
        val su = casProperties.getAuthn().getSurrogate();
        val surrogatePolicy = new HardTimeoutExpirationPolicy(su.getTgt().getTimeToKillInSeconds());
        val policy = new SurrogateSessionExpirationPolicy();
        policy.addPolicy(SurrogateSessionExpirationPolicy.POLICY_NAME_SURROGATE, surrogatePolicy);
        policy.addPolicy(BaseDelegatingExpirationPolicy.POLICY_NAME_DEFAULT,
            ticketGrantingTicketExpirationPolicyBuilder.buildTicketExpirationPolicy());
        return policy;
    }
To ticket expiration policy.

@return the expiration policy
support/cas-server-support-surrogate-core/src/main/java/org/apereo/cas/authentication/SurrogateAuthenticationExpirationPolicyBuilder.java