docs: private boolean hasNextValue(boolean update_pos) {
      final int size = iterators.length;
      for (int i = pos + 1; i < size; i++) {
        if (timestamps[i] != 0) {
          //LOG.debug("hasNextValue -> true #" + i);
          if (update_pos) {
            pos = i;
          }
          return true;
        }
      }
      //LOG.debug("hasNextValue -> false (ran out)");
      return false;
    }