protected List<String> digestIdentifier(final Collection<Object> identifiers) {
        return identifiers
            .stream()
            .map(Object::toString)
            .map(this::digestIdentifier)
            .collect(Collectors.toList());
    }
Base ticket registry class that implements common ticket-related ops.

@author Scott Battaglia
@since 3.0.0
core/cas-server-core-tickets-api/src/main/java/org/apereo/cas/ticket/registry/AbstractTicketRegistry.java