5,
        "six",
        6,
        "seven",
        7,
        "eight",
        8,
        "nine",
        9,
        "ten",
        10);
  }

  public void testOfNullKey() {
    assertThrows(NullPointerException.class, () -> ImmutableMap.of(null, 1));

    assertThrows(NullPointerException.class, () -> ImmutableMap.of("one", 1, null, 2));
  }

  public void testOfNullValue() {