I am new to Springboot and i am now currently trying to learn how to use it with facade pattern. What is the main thing to do in facade and why should i use it. I tried to do it but i am not getting it right at this moment.this is the code i did by trying to find a adrress by a city id.im just posting the code im having trouble with

this is the repository class

@Repository
public interface EmployeeAddressRepository {
        List<EmployeeAddress> findAllByAddress_City_Id(String cityid);
}

service class

@Service
public class EmployeeAddressService {
    private EmployeeAddressRepository repository;
    public List<EmployeeAddress> getallempbycityid(String cityid){
        return this.repository.findAllByAddress_City_Id(cityid);
    }
}

@Component
public class EmployeeAddressApi {
    private EmployeeAddressService employeeAddressService;
    private EmployeeService employeeService;
    @Autowired
    EmployeeAddressApi(EmployeeAddressService employeeAddress, EmployeeService employee) {
        this.employeeService = employee;
        this.employeeAddressService = employeeAddress;
    }
    public List<EmployeeAddress> getEmployeebycityId(String cityId) {
        List<EmployeeAddress> EMPADDRESSLIST = employeeAddressService.getallempbycityid(cityId);
        //adding names and emp id in list
        List<Name> namesList = new LinkedList<>();
        //sorting and getting just names
        for (EmployeeAddress ea : EMPADDRESSLIST) {
            namesList.add(employeeService.findById(ea.getStaffId()).getName())
        }
        if (namesList.isEmpty())
            return null;
        List<String> surnames=new ArrayList<>();
        for(Name n:namesList){
            surnames.add(n.getLastName)
        }
        //return surname
            return namesList;
    }
}

@RestController
@RequestMapping("/employeeaddress")
public class EmployeeAddressController {
    private EmployeeAddressApi employeeAddressApi;

    EmployeeAddressController(EmployeeAddressApi employeeAddressApi){
        this.employeeAddressApi=employeeAddressApi;
    }
    @GetMapping("/getempbycityid/{cityId}")
    public List<Name> read(@PathVariable String cityId){
        return employeeAddressApi.getEmployeebycityId(cityId)};
}
//testController
@Test
d b_read() {
    String cityid="cityid"
    String url=base_url+"/read/"+cityid;
    System.out.println("URL"+ url);
    HttpHeaders httpHeaders=new HttpHeaders();
    HttpEntity<String> entity=new HttpEntity<>(null,httpHeaders);
    ResponseEntity<String> response=restTemplate.exchange(url, HttpMethod.GET,entity,String.class);
    assertNotNull(response);
    System.out.println("allcity"+cityid;
    System.out.println("getall"+response.body();
}

I am trying to get a adress by a cityId then from that get a employee last name from the city id