*     Queue<Integer>} but not a {@code Queue<Object>}).
   * @since 8.0
   */
  public static final class Builder<B> {
    /*
     * TODO(kevinb): when the dust settles, see if we still need this or can
     * just default to DEFAULT_CAPACITY.
     */
    private static final int UNSET_EXPECTED_SIZE = -1;

    private final Comparator<B> comparator;