docs: public <S, T> MapUpdate<S, T> map(Function<K, S> keyMapper, Function<V, T> valueMapper) {
      return MapUpdate.<S, T>builder()
          .withType(type)
          .withKey(keyMapper.apply(key))
          .withValue(value == null ? null : valueMapper.apply(value))
          .withVersion(version)
          .build();
    }