code: public static <T> StreamEx<T> ofValues(Map<?, T> map) {
          return of(map.values().spliterator());
      }
docs: Returns a sequential {@code StreamEx} with values of given {@link Map} as
  its source.
  
  @param <T> the type of map keys
  @param map input map
  @return a sequential {@code StreamEx} over the values of given
  {@code Map}
  @throws NullPointerException if map is null
  @see Map#values()