code: public boolean hasItem(final String rel) {
          final String resolvedRel = curies.resolve(rel);
          return items != null && items.containsKey(resolvedRel);
      }
docs: Checks the existence of embedded items with link-relation type {@code rel}
  
  @param rel the link-relation type
  @return true, if item(s) exists, false otherwise
  
  @since 2.0.0