void loadSessions(ExecutorService executor) {
        loadRemoteSessions(executor);
        try {
            executor.shutdown();
            if ( ! executor.awaitTermination(1, TimeUnit.MINUTES))
                log.log(Level.INFO, "Executor did not terminate");
        } catch (InterruptedException e) {
            log.log(Level.WARNING, "Shutdown of executor for loading sessions failed: " + Exceptions.toMessageString(e));
        }
    }
Session repository for a tenant. Stores session state in zookeeper and file system. There are two
different session types (RemoteSession and LocalSession).

@author Ulf Lilleengen
@author hmusum
configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionRepository.java