public String logPre() {
        Optional<ApplicationId> applicationId = getOptionalApplicationId();

        // We might not be able to read application id from zookeeper
        // e.g. when the app has been deleted. Use tenant name in that case.
        return applicationId
                .filter(appId -> ! appId.equals(ApplicationId.defaultId()))
                .map(TenantRepository::logPre)
                .orElse(TenantRepository.logPre(getTenantName()));
    }
Helper to provide a log message preamble for code dealing with sessions
@return log preamble
configserver/src/main/java/com/yahoo/vespa/config/server/session/Session.java