private Instant created(File file) {
        BasicFileAttributes fileAttributes;
        try {
            fileAttributes = readAttributes(file.toPath(), BasicFileAttributes.class);
            return fileAttributes.creationTime().toInstant();
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }
A session for which we don't have a watcher, i.e. hitherto unknown to us.

@param sessionId session id for the new session
configserver/src/main/java/com/yahoo/vespa/config/server/session/SessionRepository.java