Map<K, Collection<V>> result = map;
      if (result == null) {
        result =
            map =
                Collections.unmodifiableMap(
                    Maps.transformValues(
                        delegate.asMap(), collection -> unmodifiableValueCollection(collection)));
      }
      return result;
    }

    @Override
    public Collection<Entry<K, V>> entries() {

      NavigableMap<K, V2> transformValues(
          NavigableMap<K, V1> fromMap, Function<? super V1, V2> function) {
    return transformEntries(fromMap, asEntryTransformer(function));
  }

  /**
   * Returns a view of a map whose values are derived from the original map's entries. In contrast
   * to {@link #transformValues}, this method's entry-transformation logic may depend on the key as