code: @Override
      public ScheduledFuture<?> schedule(Topic topic, long initialDelay, long period, TimeUnit unit) {
          return schedule(topic, null, initialDelay, period, unit);
      }
docs: /*
  @see
  com.ibm.websphere.event.ScheduledEventService#schedule(com.ibm.websphere
  .event.Topic, long, long, java.util.concurrent.TimeUnit)