assertEquals(asList("a", "b", "c", "d"), list);
    b.set(0, "f");
    assertEquals(asList("a", "b", "c", "d"), list);
  }

  public void testBuilderAddAll_iterator() {
    List<String> a = asList("a", "b");
    List<String> b = asList("c", "d");
    ImmutableList<String> list =
        new ImmutableList.Builder<String>().addAll(a.iterator()).addAll(b.iterator()).build();