Lists.<@Nullable String>newArrayList("hello", null, "world").iterator();
    assertEquals("[hello, null, world]", Iterators.toString(iterator));
  }

  public void testToStringEmptyIterator() {
    Iterator<String> iterator = Collections.<String>emptyList().iterator();
    assertEquals("[]", Iterators.toString(iterator));
  }

  @SuppressWarnings("JUnitIncompatibleType") // Fails with j2kt.