// HappyBirthday.javapublic class HappyBirthday {  private static final Logger log = getLogger(HappyBirthday.class);   static final String NAME = "Alex";  static final String FROM = "UIM colleagues";   public static void main(String[] args) throws Exception {    var cake = new Cake(7);    var candlesOut = new CountDownLatch(cake.size());    cake.onCandleOut(candle -> candlesOut.countDown());     log.info("Compiling wishes for {}", NAME);    for (Candle c : cake.candles()) {      c.light();      log.debug("Candle {}/{} lit", c.index() + 1, cake.size());    }    log.info("All {} candles lit", cake.size());    log.info("Happy birthday, {}!", NAME);    log.info("Signed by {}", FROM);     candlesOut.await();   // park until the cake is dark    log.info("Wish committed");  }}