@Override
  public Set<Entry<CharSequence, V>> entrySet() {
    Set<Entry<CharSequence, V>> entrySet = Sets.newHashSet();

    for (Entry<CharSequenceWrapper, V> entry : wrapperMap.entrySet()) {
      entrySet.add(new CharSequenceEntry<>(entry));
    }

    return entrySet;
  }
@Test
  public void testEntrySet() {
    CharSequenceMap<String> map = CharSequenceMap.create();
    map.put("key1", "value1");
    map.put(new StringBuilder("key2"), "value2");
    assertThat(map.entrySet()).hasSize(2);
  }