* about when we have an Object[] vs. a Comparable[] or other array type in internalArray? If we
     * used Object[], we might be able to optimize toArray() to use clone() sometimes. (See
     * cl/592273615 and cl/592273683.)
     */
    @SuppressWarnings("unchecked")
    public Builder(Comparator<? super E> comparator) {
      this.comparator = checkNotNull(comparator);
    }

    /**

     * about when we have an Object[] vs. a Comparable[] or other array type in internalArray? If we
     * used Object[], we might be able to optimize toArray() to use clone() sometimes. (See
     * cl/592273615 and cl/592273683.)
     */
    @SuppressWarnings("unchecked")
    public Builder(Comparator<? super E> comparator) {
      super(true); // don't construct guts of hash-based set builder