*/
  protected ArrayWithDuplicate<E> createArrayWithDuplicateElement() {
    E[] elements = createSamplesArray();
    E duplicate = elements[(elements.length / 2) - 1];
    elements[(elements.length / 2) + 1] = duplicate;
    return new ArrayWithDuplicate<>(elements, duplicate);
  }

  // Helper methods to improve readability of derived classes

  protected int getNumElements() {

    protected List<Character> create(Character[] elements) {
      return asList(elements);
    }
  }

  public static final class CharsAsListHeadSubListGenerator extends TestCharListGenerator {
    @Override
    protected List<Character> create(Character[] elements) {
      Character[] suffix = {Character.MIN_VALUE, Character.MAX_VALUE};
      Character[] all = concat(elements, suffix);

    @Override
    protected List<Double> create(Double[] elements) {
      return asList(elements);
    }
  }

  public static final class DoublesAsListHeadSubListGenerator extends TestDoubleListGenerator {
    @Override
    protected List<Double> create(Double[] elements) {
      Double[] suffix = {Double.MIN_VALUE, Double.MAX_VALUE};
      Double[] all = concat(elements, suffix);
      return asList(all).subList(0, elements.length);

    protected List<Character> create(Character[] elements) {
      return asList(elements);
    }
  }

  public static final class CharsAsListHeadSubListGenerator extends TestCharListGenerator {
    @Override
    protected List<Character> create(Character[] elements) {
      Character[] suffix = {Character.MIN_VALUE, Character.MAX_VALUE};
      Character[] all = concat(elements, suffix);

    if (length == 0) {
      return new Object[0];
    }
    @Nullable Object[] result = new Object[length];
    System.arraycopy(elements, offset, result, 0, length);
    return result;
  }

  @CanIgnoreReturnValue
  private static @Nullable Object[] fillArray(Iterable<?> elements, @Nullable Object[] array) {
    int i = 0;
    for (Object element : elements) {

  /**
   * Creates a new {@code HashMultiset} containing the specified elements.
   *
   * <p>This implementation is highly efficient when {@code elements} is itself a {@link Multiset}.
   *
   * @param elements the elements that the multiset should contain
   */
  public static <E extends @Nullable Object> HashMultiset<E> create(
      Iterable<? extends E> elements) {

  static final RegularImmutableSet<Object> EMPTY =
      new RegularImmutableSet<>(EMPTY_ARRAY, 0, EMPTY_ARRAY, 0, 0);

  // The first `size` elements are non-null.
  @VisibleForTesting final transient @Nullable Object[] elements;
  private final transient int hashCode;
  // the same values as `elements` in hashed positions (plus nulls)
  @VisibleForTesting final transient @Nullable Object[] table;
  // 'and' with an int to get a valid table index.

    return new Unhashables();
  }

  @Override
  public T create(Object... elements) {
    UnhashableObject[] array = createArray(elements.length);
    int i = 0;
    for (Object e : elements) {
      array[i++] = (UnhashableObject) e;
    }
    return create(array);
  }

  /**
   * Creates a new collection containing the given elements; implement this method instead of {@link
   * #create(Object...)}.
   */

   * of their elements."
   *
   * </blockquote>
   */
  RESTRICTS_ELEMENTS,

  /**
   * Indicates that a collection has a well-defined ordering of its elements. The ordering may
   * depend on the element values, such as a {@link SortedSet}, or on the insertion ordering, such
   * as a {@link LinkedHashSet}. All list tests and sorted-collection tests automatically specify
   * this feature.
   */

    suite.addTest(
        SetTestSuiteBuilder.using(
                new TestStringSetGenerator() {
                  @Override
                  protected Set<String> create(String[] elements) {
                    return CompactLinkedHashSet.create(Arrays.asList(elements));
                  }
                })
            .named("CompactLinkedHashSet")
            .withFeatures(allFeatures)
            .createTestSuite());
    return suite;