code: protected void rehash(int newCapacity)
    {
      HashIntSet rehashed = new HashIntSet(newCapacity);
      @SuppressWarnings("hiding")
      int[] cells = rehashed.cells;
      for (int element : this.cells) {
        if (element < 0)
        // removed or empty
        {
          continue;
        }
  
        // add the element
        cells[-(rehashed.findElementOrEmpty(element) + 1)] = element;
      }
      this.cells = cells;
      freecells = newCapacity - size;
      modCount++;
    }
docs: Rehashes to a bigger size.