code: public static Set<Emoji> getForTag(String tag) {
      if (tag == null) {
        return null;
      }
      return EMOJIS_BY_TAG.get(tag);
    }
docs: Returns all the {@link com.vdurmont.emoji.Emoji}s for a given tag.
  
  @param tag the tag
  
  @return the associated {@link com.vdurmont.emoji.Emoji}s, null if the tag
  is unknown