docs: public ScheduledFuture<?> iterateAtFixedRate(long initialDelay, long period, TimeUnit unit, Iterator<Runnable> commands)
      {
          ensureWaiterRunning();
          log(logLevel, "iterateAtFixedRate(%d, %d, %s)", initialDelay, period, unit);
          RunnableScheduledFutureImpl future = new RunnableScheduledFutureImpl(new RunnableIterator(commands), initialDelay, period, unit, false);
          delayQueue.add(future);
          return future;
      }