code: public static Specification<JpaTarget> byControllerIdWithTagsInJoin(final Collection<String> controllerIDs) {
          return (targetRoot, query, cb) -> {
              final Predicate predicate = targetRoot.get(JpaTarget_.controllerId).in(controllerIDs);
              targetRoot.fetch(JpaTarget_.tags, JoinType.LEFT);
              query.distinct(true);
              return predicate;
          };
      }
docs: {@link Specification} for retrieving {@link Target}s including
  {@link TargetTag}s.
  
  @param controllerIDs
  to search for
  
  @return the {@link Target} {@link Specification}