docs: @Override
    public int[] toArray() {
      final int[] array = new int[this.getCardinality()];
      int pos = 0, pos2 = 0;
      while (pos < this.highLowContainer.size()) {
        final int hs = BufferUtil.toIntUnsigned(this.highLowContainer.getKeyAtIndex(pos)) << 16;
        final MappeableContainer c = this.highLowContainer.getContainerAtIndex(pos++);
        c.fillLeastSignificant16bits(array, pos2, hs);
        pos2 += c.getCardinality();
      }
      return array;
    }