public void close() {
        directoryCache.close();
        fileDistributionFactory.close();
        try {
            zkCacheExecutor.shutdown();
            checkForRemovedApplicationsService.shutdown();
            zkApplicationWatcherExecutor.shutdownAndWait();
            zkSessionWatcherExecutor.shutdownAndWait();
            zkCacheExecutor.awaitTermination(50, TimeUnit.SECONDS);
            checkForRemovedApplicationsService.awaitTermination(50, TimeUnit.SECONDS);
        }
        catch (InterruptedException e) {
            log.log(Level.WARNING, "Interrupted while shutting down.", e);
            Thread.currentThread().interrupt();
        }
    }
A helper to format a log preamble for messages with a tenant

@param tenant tenant
@return the log string
configserver/src/main/java/com/yahoo/vespa/config/server/tenant/TenantRepository.java