@Query("SELECT u FROM AppUser u LEFT OUTER JOIN fetch u.userRights a LEFT OUTER JOIN fetch u.userGroups g LEFT OUTER JOIN fetch u.userGroups ug LEFT OUTER JOIN FETCH ug.groupRights where u.login = :login")
public Optional<AppUser> findOneWithCompleteRights(@Param("login") String login);

Caused by: javax.persistence.PersistenceException: org.hibernate.loader.MultipleBagFetchException: cannot simultaneously fetch multiple bags