assertEquals(asList("5", "2", "3", "4", "6"), toList);
    fromList.remove(Integer.valueOf(2));
    assertEquals(asList("5", "3", "4", "6"), toList);
    fromList.remove(2);
    assertEquals(asList("5", "3", "6"), toList);

    /* toList modifications reflected in fromList */
    toList.remove(2);
    assertEquals(asList(5, 3), fromList);
    toList.remove("5");
    assertEquals(asList(3), fromList);