@SuppressWarnings("UseCollectionConstructor") // test of factory method
    HashMap<Integer, Integer> map = Maps.newHashMap();
    assertEquals(emptyMap(), map);
  }

  public void testHashMapWithInitialMap() {
    Map<String, Integer> original = new TreeMap<>();
    original.put("a", 1);
    original.put("b", 2);
    original.put("c", 3);
    @SuppressWarnings("UseCollectionConstructor") // test of factory method