When nullSafeSet from Hibernate UserType is calling

Question

I created UserType for password encryption/decryption. And after select entities from db, UserType automaticly makes update, why?

Query query = entityManager.createNamedQuery(User.FIND_ALL);
List<User> result = query.getResultList();
// here in background is calling UserType.nullSafeGet() for password decryption, and this is OK
result.forEach(user -> entityManager.detach(user));
return result;
// here in background is calling UserType.nullSafeSet() for password encryption and trying to make UPDATE in db. Why?