// Controller
@RequestMapping(value = "/tickets", method = RequestMethod.GET)
    public ResponseEntity<List<TicketDto>> getAllTickets() {
        List<TicketDto> tickets = ticketService.findAllTickets(getUser());
        return new ResponseEntity<List<TicketDto>>(tickets, HttpStatus.OK);
    }
private User getUser() {
	Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
	String name = authentication.getName();
	return userService.findByEmail(name);
}

// Service
@Service
public class TicketServiceImpl implements TicketService {

    @Autowired
    private TicketRepository ticketRepository;

    @Transactional(readOnly = true)
    public List<TicketDto> findAllTickets(User user) {
        List<Ticket> ticketList = new ArrayList<>();
        if (user.getRole().equals(Role.EMPLOYEE)) {
            ticketList = ticketRepository.findAllTicketsByEmployee(user.getId());
        } else if (user.getRole().equals(Role.MANAGER)) {
            ticketList = ticketRepository.findAllTicketsByManager(user.getId());
        } else if (user.getRole().equals(Role.ENGINEER)) {
            ticketList = ticketRepository.findAllTicketsByEngineer(user.getId());
        }
        TicketConverter ticketConverter = new TicketConverter();
        List<TicketDto> ticketListDto = ticketConverter.convertEntityListToDtoList(ticketList);
        return ticketListDto;
    }

   // ...
}