@GetMapping("/api/link-unit-all-buildings")
public UnitBuildingsDto getAllBuildings( @RequestParam("id") long id ) {

    UnitBuildingsDto unit_building_dto;

    EntityManager em = null;
    EntityTransaction tran = null;

    try {

        em = Database.createEntityManager();
        tran = em.getTransaction();

        tran.begin();

            List< BuildingDto > buildings = em.createQuery("SELECT b FROM Building b", Building.class)
                                              .getResultList()
                                              .stream()
                                              .map(BuildingDto::make)
                                              .collect(Collectors.toList());

        tran.commit();

        Unit u = em.find(Unit.class, id);
        if(u == null)
            throw new NotFoundException("link-unit-all-buildings");

        unit_building_dto.setUnit( UnitDto.make( u ) );
        unit_building_dto.setBuildings( buildings );

    } catch (RuntimeException exc) {
        if (tran != null && tran.isActive())
            tran.rollback();

        throw exc;
    } finally {
        if (em != null)
            em.close();
    }

    return unit_building_dto;
}