Set<Element> set = Sets.newHashSetWithExpectedSize(size);
    while (set.size() < size) {
      set.add(newElement());
    }
    return set;
  }

  private Element newElement() {
    int value = random.nextInt();
    return isUserTypeFast ? new Element(value) : new SlowElement(value);
  }

  static class Element implements Comparable<Element> {
    final int hash;

    Element(int hash) {

    Set<Element> set = Sets.newHashSetWithExpectedSize(size);
    while (set.size() < size) {
      set.add(newElement());
    }
    return set;
  }

  private Element newElement() {
    int value = random.nextInt();
    return isUserTypeFast ? new Element(value) : new SlowElement(value);
  }

  static class Element implements Comparable<Element> {
    final int hash;

    Element(int hash) {

            }
            Element newElement = document.createElement("programlisting");
            //we're making an assumption that all <pre> elements contain java code
            //this should mostly be true :)
            //if it isn't true then the syntax highlighting won't spoil the view too much anyway
            newElement.setAttribute("language", "java");
            nodes.push(newElement);
            return true;
        }

    throw new UnsupportedOperationException();
  }

  public final boolean remove(@Nullable Object object) {
    throw new UnsupportedOperationException();
  }

  public final boolean addAll(Collection<? extends E> newElements) {
    throw new UnsupportedOperationException();
  }

  public final boolean removeAll(Collection<?> oldElements) {
    throw new UnsupportedOperationException();
  }

  public boolean add(E element) {
    offer(element);
    return true;
  }

  @CanIgnoreReturnValue
  @Override
  public boolean addAll(Collection<? extends E> newElements) {
    boolean modified = false;
    for (E element : newElements) {
      offer(element);
      modified = true;
    }
    return modified;
  }

  /**

  @Override
  public int lastIndexOf(@Nullable Object object) {
    return (object == null) ? -1 : Lists.lastIndexOfImpl(this, object);
  }

  public final boolean addAll(int index, Collection<? extends E> newElements) {
    throw new UnsupportedOperationException();
  }

  public final E set(int index, E element) {
    throw new UnsupportedOperationException();
  }

  public final void add(int index, E element) {

   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final boolean addAll(Collection<? extends E> newElements) {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the collection unmodified.
   *
   * @throws UnsupportedOperationException always

   * @deprecated Unsupported operation.
   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final boolean addAll(Collection<? extends E> newElements) {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the collection unmodified.
   *
   * @throws UnsupportedOperationException always

   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final boolean addAll(int index, Collection<? extends E> newElements) {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the list unmodified.
   *
   * @throws UnsupportedOperationException always

   */
  @CanIgnoreReturnValue
  @Deprecated
  @Override
  @DoNotCall("Always throws UnsupportedOperationException")
  public final boolean addAll(int index, Collection<? extends E> newElements) {
    throw new UnsupportedOperationException();
  }

  /**
   * Guaranteed to throw an exception and leave the list unmodified.
   *
   * @throws UnsupportedOperationException always