code: public static Tags concat(@Nullable Iterable<? extends Tag> tags, @Nullable Iterable<Tag> otherTags) {
          return Tags.of(tags).and(otherTags);
      }
docs: Return a new {@code Tags} instance by concatenating the specified collections of tags.
  
  @param tags      the first set of tags
  @param otherTags the second set of tags
  @return the merged tags