public synchronized void advanceTime(long time) {
        long currentTime = getCurrentTimeInMillis();
        this.currentTime += time;
        log.log(Level.FINE, () -> "Time advanced by " + time + " ms. Time increased from " + currentTime + " to " + (currentTime + time));
        notifyAll();
    }
FakeTimer

Used to fake timing for unit test purposes.
clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/FakeTimer.java