docs: public boolean hasNext() {
      final int size = iterators.length;
      for (int i = 0; i < size; i++) {
        // As long as any of the iterators has a data point with a timestamp
        // that falls within our interval, we know we have at least one next.
        if ((timestamps[size + i] & TIME_MASK) <= end_time) {
          //LOG.debug("hasNext #" + (size + i));
          return true;
        }
      }
      //LOG.debug("No hasNext (return false)");
      return false;
    }