code: static <T> ItemsSketch<T> copy(final ItemsSketch<T> sketch) {
      final ItemsSketch<T> qsCopy = ItemsSketch.getInstance(sketch.k_, sketch.comparator_);
      qsCopy.n_ = sketch.n_;
      qsCopy.minValue_ = sketch.getMinValue();
      qsCopy.maxValue_ = sketch.getMaxValue();
      qsCopy.combinedBufferItemCapacity_ = sketch.getCombinedBufferAllocatedCount();
      qsCopy.baseBufferCount_ = sketch.getBaseBufferCount();
      qsCopy.bitPattern_ = sketch.getBitPattern();
      final Object[] combBuf = sketch.getCombinedBuffer();
      qsCopy.combinedBuffer_ = Arrays.copyOf(combBuf, combBuf.length);
      return qsCopy;
    }
docs: Returns a copy of the given sketch
  @param <T> the data type
  @param sketch the given sketch
  @return a copy of the given sketch