code: private static List<Attribute> getResolvableAttrs(EntityType entityType, Fetch fetch) {
      return Streams.stream(entityType.getAtomicAttributes())
          .filter(EntityTypeUtils::isReferenceType)
          .filter(attr -> attr.getExpression() == null)
          .filter(attr -> fetch.hasField(attr.getName()))
          .collect(Collectors.toList());
    }
docs: Return all resolvable attributes: non-computed reference attributes defined in fetch
  
  @param entityType entity meta data
  @param fetch entity fetch
  @return resolved attributes