@Service
public class ContractService {
    
    @Autowired
    private ContractRepository contractRepository;

    @Transactional
    public Contract updateContract(Long id, Contract newContractDetails) {
        return contractRepository.findById(id).map(contract -> {
            contract.setName(newContractDetails.getName());
            contract.setStartDate(newContractDetails.getStartDate());
            contract.setEndDate(newContractDetails.getEndDate());
            return contractRepository.save(contract);
        }).orElseGet(() -> {
            newContractDetails.setId(id);
            return contractRepository.save(newContractDetails);
        });
    }
}