LockMetrics getLockMetrics(String lockPath) {
        return metricsByLockPath.computeIfAbsent(lockPath, __ -> new LockMetrics());
    }
Returns the ThreadLockStats holding the lock on the path, but the info may be outdated already
on return, either no-one holds the lock or another thread may hold the lock.
zkfacade/src/main/java/com/yahoo/vespa/curator/stats/LockStats.java