code: public void combine(LongSummaryStatistics other) {
          count += other.count;
          sum += other.sum;
          min = Math.min(min, other.min);
          max = Math.max(max, other.max);
      }
docs: Combines the state of another {@code LongSummaryStatistics} into this
  one.
  
  @param other another {@code LongSummaryStatistics}
  @throws NullPointerException if {@code other} is null