void lockAcquired() {
        lockState = LockState.ACQUIRED;
        lockAcquiredInstant = Optional.of(Instant.now());
        activeLockedInterval = Optional.of(lockMetrics.lockAcquired(reentry, activeAcquireInterval));
    }
Fill in the stack trace starting at the caller's stack frame.
zkfacade/src/main/java/com/yahoo/vespa/curator/stats/LockAttempt.java