public Instant getTimeAcquireEndedOrNow() {
        return lockAcquiredInstant.orElseGet(() -> getTimeTerminalStateWasReached().orElseGet(Instant::now));
    }
Information about a lock.

<p>Should be mutated by a single thread, except {@link #fillStackTrace()} which can be
invoked by any threads.  Other threads may see an inconsistent state of this instance.</p>

@author hakon
zkfacade/src/main/java/com/yahoo/vespa/curator/stats/LockAttempt.java