*       one with {@link CharSequence#charAt(int)}.
   *   <li>use {@link Appendable#append(CharSequence)} in {@link #copyTo(Appendable)} and {@link
   *       #copyTo(CharSink)}. We know this is correct since strings are immutable and so the length
   *       can't change, and it is faster because many writers and appendables are optimized for

  private ListGenerators() {}

  public static class ImmutableListOfGenerator extends TestStringListGenerator {
    @Override
    protected List<String> create(String[] elements) {
      return ImmutableList.copyOf(elements);
    }
  }

  public static class BuilderAddListGenerator extends TestStringListGenerator {
    @Override
    protected List<String> create(String[] elements) {

      return ImmutableSortedSet.copyOf(elements);
    }
  }

  public static class ImmutableSortedSetHeadsetGenerator extends TestStringSortedSetGenerator {
    @Override
    protected SortedSet<String> create(String[] elements) {
      List<String> list = Lists.newArrayList(elements);
      list.add("zzz");
      return ImmutableSortedSet.copyOf(list).headSet("zzy");
    }
  }

    Random random = new Random();
    while (set.size() < size) {
      set.add(random.nextInt());
    }
    List<Integer> list = new ArrayList<>(set);
    inputOrder.arrange(list);
    input = ImmutableList.copyOf(list);
  }

  @Benchmark
  int collections(int reps) {
    int dummy = 0;
    // Yes, this could be done more elegantly
    if (mutable) {
      for (int i = 0; i < reps; i++) {

    String[] array = new String[0];
    Multiset<String> multiset = ImmutableMultiset.copyOf(array);
    assertTrue(multiset.isEmpty());
  }

  public void testCreation_arrayOfOneElement() {
    String[] array = new String[] {"a"};
    Multiset<String> multiset = ImmutableMultiset.copyOf(array);
    assertEquals(HashMultiset.create(asList("a")), multiset);
  }

    assertEquals(asList("a", "b", "a"), list);
    List<String> mutableList = asList("a", "b");
    list = ImmutableList.copyOf(mutableList);
    mutableList.set(0, "c");
    assertEquals(asList("a", "b"), list);
  }

  public void testCopyOf_collectionContainingNull() {
    Collection<@Nullable String> c = MinimalCollection.of("a", null, "b");

  @Override
  protected <E extends Comparable<? super E>> Set<E> copyOf(E[] elements) {
    return ImmutableSet.copyOf(elements);
  }

  @Override
  protected <E extends Comparable<? super E>> Set<E> copyOf(Collection<? extends E> elements) {
    return ImmutableSet.copyOf(elements);
  }

  @Override
  protected <E extends Comparable<? super E>> Set<E> copyOf(Iterable<? extends E> elements) {

     */
    assertThat(ImmutableDoubleArray.copyOf(new double[0]))
        .isSameInstanceAs(ImmutableDoubleArray.of());
  }

  public void testCopyOf_array_nonempty() {
    double[] array = new double[] {0, 1, 3};
    ImmutableDoubleArray iia = ImmutableDoubleArray.copyOf(array);
    array[2] = 2;
    assertThat(iia.asList()).containsExactly(0.0, 1.0, 3.0).inOrder();
  }

            if (o.isPresent()) {
                had++;
                items.addAll(o.get());
            }
        }
        return had == 0 ? Optional.empty() : Optional.of(List.copyOf(items));
    }

    protected Optional<Map<String, String>> collectMapIfPresentOrEmpty(
            Function<O, Optional<Map<String, String>>> getter) {
        int had = 0;

    ImmutableList<Cell<R, C, V>> cellList = ImmutableList.copyOf(cells);
    for (Cell<R, C, V> cell : cells) {
      rowSpaceBuilder.add(cell.getRowKey());
      columnSpaceBuilder.add(cell.getColumnKey());
    }

    ImmutableSet<R> rowSpace =
        (rowComparator == null)
            ? ImmutableSet.copyOf(rowSpaceBuilder)
            : ImmutableSet.copyOf(ImmutableList.sortedCopyOf(rowComparator, rowSpaceBuilder));