code: private boolean isViewElementFindableOrList(Field field) {
          Class<?> fieldType = field.getType();
          return View.class.isAssignableFrom(fieldType)
                  || Element.class.isAssignableFrom(fieldType)
                  || Findable.class.isAssignableFrom(fieldType)
                  || List.class.isAssignableFrom(fieldType);
      }
docs: Those are only supported types which make sense to look at.