TreeMap<Integer, Integer> map = Maps.newTreeMap(SOME_COMPARATOR);
    assertEquals(emptyMap(), map);
    assertSame(SOME_COMPARATOR, map.comparator());
  }

  public void testTreeMapWithInitialMap() {
    SortedMap<Integer, Integer> map = Maps.newTreeMap();
    map.put(5, 10);
    map.put(3, 20);
    map.put(1, 30);
    TreeMap<Integer, Integer> copy = Maps.newTreeMap(map);
    assertEquals(copy, map);

    TreeMap<Integer, Integer> map = Maps.newTreeMap(SOME_COMPARATOR);
    assertEquals(emptyMap(), map);
    assertSame(SOME_COMPARATOR, map.comparator());
  }

  public void testTreeMapWithInitialMap() {
    SortedMap<Integer, Integer> map = Maps.newTreeMap();
    map.put(5, 10);
    map.put(3, 20);
    map.put(1, 30);
    TreeMap<Integer, Integer> copy = Maps.newTreeMap(map);
    assertEquals(copy, map);

     * @param <V> the value type of {@link TreeMap}
     * @return a new instance of {@link TreeMap}
     * @see TreeMap#TreeMap()
     */
    public static <K, V> TreeMap<K, V> newTreeMap() {
        return new TreeMap<>();
    }

    /**
     * Creates and returns a new instance of {@link TreeMap}.
     *
     * @param <K> the key type of {@link TreeMap}