public abstract Builder<E> add(E element);

    @CanIgnoreReturnValue
    public Builder<E> add(E... elements) {
      checkNotNull(elements); // for GWT
      for (E element : elements) {
        add(checkNotNull(element));
      }
      return this;
    }

    @CanIgnoreReturnValue
    public Builder<E> addAll(Iterable<? extends E> elements) {
      checkNotNull(elements); // for GWT

  @JsMethod(name = "of")
  static <E> ImmutableSet<E> jsOf(E... elements) {
    return copyOf(elements);
  }

  @JsMethod
  public static <E> ImmutableSet<E> copyOf(E[] elements) {
    checkNotNull(elements);
    switch (elements.length) {
      case 0:
        return of();
      case 1:
        return of(elements[0]);
      default:
        return create(elements);
    }
  }

  /**
   * Returns a new array that prepends {@code element} to {@code array}.
   *
   * @param element the element to prepend to the front of {@code array}
   * @param array the array of elements to append
   * @return an array whose size is one larger than {@code array}, with {@code element} occupying
   *     the first position, and the elements of {@code array} occupying the remaining elements.
   */

    while (iterator.hasNext()) {
      T element = iterator.next();
      if (!predicate.apply(element)) {
        return false;
      }
    }
    return true;
  }

  /**
   * Returns the first element in {@code iterator} that satisfies the given predicate; use this
   * method only when such an element is known to exist. If no such element is found, the iterator

    public Builder<E> add(E element) {
      super.add(element);
      return this;
    }

    /**
     * Adds each element of {@code elements} to the {@code ImmutableSortedSet}, ignoring duplicate
     * elements (only the first duplicate element is added).
     *
     * @param elements the elements to add
     * @return this {@code Builder} object
     * @throws NullPointerException if {@code elements} contains a null element

     */
    @CanIgnoreReturnValue
    public Builder<E> addCopies(E element, int occurrences) {
      contents.add(checkNotNull(element), occurrences);
      return this;
    }

    /**
     * Adds or removes the necessary occurrences of an element such that the element attains the
     * desired count.
     *
     * @param element the element to add or remove occurrences of

  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 a new array that prepends {@code element} to {@code array}.
   *
   * @param element the element to prepend to the front of {@code array}
   * @param array the array of elements to append
   * @return an array whose size is one larger than {@code array}, with {@code element} occupying
   *     the first position, and the elements of {@code array} occupying the remaining elements.
   */

      for (int i = 0; i < 100; i++) {
        Element element = Element.values()[random.nextInt(range)];
        elements.add(element);
        queue.add(element);
      }
      Iterator<Element> queueIterator = queue.iterator();
      int remaining = queue.size();
      while (queueIterator.hasNext()) {
        Element element = queueIterator.next();
        remaining--;

  public static boolean contains(Iterable<?> iterable, @Nullable Object element) {
    if (iterable instanceof Collection) {
      Collection<?> collection = (Collection<?>) iterable;
      return Collections2.safeContains(collection, element);
    }
    return Iterators.contains(iterable.iterator(), element);
  }

  /**
   * Removes, from an iterable, every element that belongs to the provided collection.
   *