void notifyOfThreadHoldingLock(Thread currentThread, String lockPath) {
        Thread oldThread = lockPathsHeld.put(lockPath, currentThread);
        if (oldThread != null) {
            getLockMetrics(lockPath).incrementAcquireWithoutReleaseCount();
            logger.warning("Thread " + currentThread.getName() + " reports it has the lock on " +
                           lockPath + ", but thread " + oldThread.getName() +
                           " has not reported it released the lock");
        }
    }
Must be invoked only after the first and non-reentry acquisition of the lock.
zkfacade/src/main/java/com/yahoo/vespa/curator/stats/LockStats.java