code: private static boolean emitEvents(WatchService watchService,
              Subscriber<? super WatchEvent<?>> subscriber, long pollDurationMs,
              long pollIntervalMs) {
          // get the first event
          WatchKey key = nextKey(watchService, subscriber, pollDurationMs);
  
          if (key != null) {
              if (subscriber.isUnsubscribed())
                  return false;
              // we have a polled event, now we traverse it and
              // receive all the states from it
              for (WatchEvent<?> event : key.pollEvents()) {
                  if (subscriber.isUnsubscribed())
                      return false;
                  else
                      subscriber.onNext(event);
              }
  
              boolean valid = key.reset();
              if (!valid && !subscriber.isUnsubscribed()) {
                  subscriber.onCompleted();
                  return false;
              } else if (!valid)
                  return false;
          }
          return true;
      }
docs: returns true if and only there may be more events