@Component
public class EntityGenerator {
    @PersistenceUnit
    private final EntityManagerFactory entityManagerFactory;

    public EntityGenerator(@Autowired EntityManagerFactory entityManagerFactory) {
        this.entityManagerFactory = entityManagerFactory;
    }

    public <T extends Persistable<Long>> Collection<T> generate(Class<T> entityClass, int quantity, String actorIdentity) {
        Authentication authentication = MockedAuthentication.create(actorIdentity, "all");
        SecurityContextHolder.getContext().setAuthentication(authentication);
        EntityManager manager = entityManagerFactory.createEntityManager();
        manager.getTransaction().begin();
        ArrayList<T> entities = new ArrayList<>();
        for (int i = 0; i < quantity; i++) {
            try {
                T entity = entityClass.getDeclaredConstructor().newInstance();
                manager.persist(entity);
                entities.add(entity);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
        manager.getTransaction().commit();
        manager.close();
        SecurityContextHolder.clearContext();
        return entities;
    }
}