@Service

public class UserService {

​

    @Autowired

    private TransactionHandler transactionHandler;

​

    public boolean addUsers(List<User> users) {

        for (User user : users) {

            transactionHandler.runInTransaction(() -> addUser(user.getUsername, user.getPassword));

        }

    }

​

    private boolean addUser(String username, String password) {

        // TODO call userRepository

    }

}

​

@Service

public class TransactionHandler {

​

    @Transactional(propagation = Propagation.REQUIRED)

    public <T> T runInTransaction(Supplier<T> supplier) {

        return supplier.get();

    }

​

    @Transactional(propagation = Propagation.REQUIRES_NEW)

    public <T> T runInNewTransaction(Supplier<T> supplier) {

        return supplier.get();

    }

}