protected int cleanInternal() {
        try (val expiredTickets = ticketRegistry.stream().filter(Objects::nonNull).filter(Ticket::isExpired)) {
            val ticketsDeleted = expiredTickets.mapToInt(this::cleanTicket).sum();
            LOGGER.info("[{}] expired tickets removed.", ticketsDeleted);
            return ticketsDeleted;
        }
    }
This is {@link DefaultTicketRegistryCleaner}.

@author Misagh Moayyed
@since 5.0.0
core/cas-server-core-tickets-api/src/main/java/org/apereo/cas/ticket/registry/DefaultTicketRegistryCleaner.java