void addTopLevelLockAttempt(LockAttempt lockAttempt) {
        // guard against recordings that are too long - to cap the memory used
        if (lockAttempts.size() < MAX_TOP_LEVEL_LOCK_ATTEMPTS) {
            lockAttempts.add(lockAttempt);
        }
    }
Note: A LockAttempt may have nested lock attempts.
zkfacade/src/main/java/com/yahoo/vespa/curator/stats/RecordedLockAttempts.java