@Override
  public int hashCode() {
    return Objects.hashCode(wrapperMap);
  }
@Test
  public void testHashCode() {
    CharSequenceMap<String> map1 = CharSequenceMap.create();
    map1.put(new StringBuilder("key"), "value");

    CharSequenceMap<String> map2 = CharSequenceMap.create();
    map2.put("key", "value");

    assertThat(map1.hashCode()).isEqualTo(map2.hashCode());
  }