spring-boot / jpa : do DTO's typically contain lists?

Do java DTO's typically contain lists? Or are they normally just a flat structure? I have searched around and not been able to find any examples of DTO's that contain lists.

Say I have a constructor like this:

public WidgetDTO(String name, String type, List<Tag> tagList) {
  this.name = name;
  this.type = type;
  this.tagList = tagList;
}

and in my repository I have this:

CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
CriteriaQuery<WidgetDTO> query = criteriaBuilder.createQuery(WidgetDTO.class);
Root<Widget> root = query.from(Widget.class);

can I build this with just a join, as I do when pulling the entity from the db?

Join<Widget, Tag> tagJoin = root.join(Widget_.tagList);

or do I need to do a subquery? Or should I skip lists altogether? When trying to do a join as above I was getting an error similar to :

Unable to locate appropriate constructor on class [com.mypackage.Widget]

thanks