}
    for (int j = 0; j < 1000; j++) {
      builder.add(9);
    }
    ImmutableSortedSet<Integer> unused = builder.build();
    assertThat(compares[0]).isAtMost(10000);
    // hopefully something quadratic would have more digits
  }

  public static <E extends @Nullable Object> CopyOnWriteArrayList<E> newCopyOnWriteArrayList(
      Iterable<? extends E> elements) {
    // We copy elements to an ArrayList first, rather than incurring the
    // quadratic cost of adding them to the COWAL directly.
    Collection<? extends E> elementsCollection =
        (elements instanceof Collection)
            ? (Collection<? extends E>) elements
            : newArrayList(elements);