ActiveInterval lockAcquired(boolean reentry, ActiveInterval acquireInterval) {
        acquireInterval.close();
        if (reentry) return () -> {};
        acquireSucceededCount.incrementAndGet();
        cumulativeAcquireSucceededCount.incrementAndGet();
        return lockedStats.startNewInterval();
    }
Returns a Runnable that must be invoked when the acquire() finishes.
zkfacade/src/main/java/com/yahoo/vespa/curator/stats/LockMetrics.java