* undocumented and subject to change.
   *
   * <p>Note that if {@code list} is a {@code List<String>}, then {@code ImmutableList.copyOf(list)}
   * returns an {@code ImmutableList<String>} containing each of the strings in {@code list}, while
   * {@code ImmutableList.of(list)} returns an {@code ImmutableList<List<String>>} containing one
   * element (the given list itself).
   *

  @SuppressWarnings("unchecked")
  public static <E> ImmutableList<E> of() {
    return (ImmutableList<E>) RegularImmutableList.EMPTY;
  }

  public static <E> ImmutableList<E> of(E element) {
    return new SingletonImmutableList<E>(checkNotNull(element));
  }

  public static <E> ImmutableList<E> of(E e1, E e2) {
    return new RegularImmutableList<E>(ImmutableList.<E>nullCheckedList(e1, e2));
  }

   * undocumented and subject to change.
   *
   * <p>Note that if {@code list} is a {@code List<String>}, then {@code ImmutableList.copyOf(list)}
   * returns an {@code ImmutableList<String>} containing each of the strings in {@code list}, while
   * {@code ImmutableList.of(list)} returns an {@code ImmutableList<List<String>>} containing one
   * element (the given list itself).
   *