* @since 3.0
   */
  public static <E> ImmutableList<E> copyOf(E[] elements) {
    switch (elements.length) {
      case 0:
        return of();
      case 1:
        return of(elements[0]);
      default:
        return construct(elements.clone());
    }
  }

  /**

    public int count(@Nullable Object element) {
      for (Entry<E> entry : entrySet()) {
        if (Objects.equal(entry.getElement(), element)) {
          return entry.getCount();
        }
      }
      return 0;
    }

    @Override
    public int add(E element, int occurrences) {
      checkArgument(occurrences >= 0);
      Integer frequency = backingMap.get(element);
      if (frequency == null) {

    public int count(@Nullable Object element) {
      for (Entry<E> entry : entrySet()) {
        if (Objects.equal(entry.getElement(), element)) {
          return entry.getCount();
        }
      }
      return 0;
    }

    @Override
    public int add(E element, int occurrences) {
      checkArgument(occurrences >= 0);
      Integer frequency = backingMap.get(element);
      if (frequency == null) {

    }

    @Override
    public boolean add(@ParametricNullness E element) {
      checkArgument(predicate.apply(element));
      return unfiltered.add(element);
    }

    @Override
    public boolean addAll(Collection<? extends E> collection) {
      for (E element : collection) {
        checkArgument(predicate.apply(element));
      }
      return unfiltered.addAll(collection);
    }

  }

  protected void expectMissingKeys(K... elements) {
    for (K element : elements) {
      assertFalse("Should not contain key " + element, getMap().containsKey(element));
    }
  }

  protected void expectMissingValues(V... elements) {
    for (V element : elements) {
      assertFalse("Should not contain value " + element, getMap().containsValue(element));
    }
  }

  public void testHashCode_containingNull() {
    Collection<E> elements = getSampleElements(getNumElements() - 1);
    int expectedHashCode = 0;
    for (E element : elements) {
      expectedHashCode += ((element == null) ? 0 : element.hashCode());
    }

    elements.add(null);
    collection = getSubjectGenerator().create(elements.toArray());
    assertEquals(

    /**
     * Returns the number of occurrences of {@code element} in this multiset.
     *
     * @param element the element to look for
     * @return the nonnegative number of occurrences of the element
     */
    @Override
    public int count(@Nullable Object element) {
      try {
        return unbox(countMap.get(element));
      } catch (NullPointerException | ClassCastException e) {
        return 0;

  public E floor(E element) {
    int index = headIndex(element, true) - 1;
    return (index == -1) ? null : elements.get(index);
  }

  @Override
  @CheckForNull
  public E ceiling(E element) {
    int index = tailIndex(element, true);
    return (index == size()) ? null : elements.get(index);
  }

  @Override
  @CheckForNull
  public E higher(E element) {
    int index = tailIndex(element, false);

    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() {
    return getSubjectGenerator().getCollectionSize().getNumElements();
  }

  @Override
  public int indexOf(@CheckForNull Object element) {
    return delegate().indexOf(element);
  }

  @Override
  public int lastIndexOf(@CheckForNull Object element) {
    return delegate().lastIndexOf(element);
  }

  @Override
  public ListIterator<E> listIterator() {
    return delegate().listIterator();
  }

  @Override
  public ListIterator<E> listIterator(int index) {