i keep getting error "Attribute value must be constant". can smb help me out?

@Endpoint
public class MyEndpoint {

    @Autowired
    MyService myService;
    @Autowired
    AppConfig appConfig;
    private final String SOAP_NAMESPACE=appConfig.getSoapNamespace();
    
    @PayloadRoot(namespace = SOAP_NAMESPACE,localPart = "idCheckRequest")
    @ResponsePayload
    public idCheckResponseDTO checkId(@RequestPayload idCheckRequestDTO idCheckRequestDTO) throws IOException {
        //code
    }
}

@Endpoint
public class MyEndpoint {

    @Autowired
    MyService myService;
    @Autowired
    AppConfig appConfig;
    private final String SOAP_NAMESPACE=appConfig.getSoapNamespace();
    
    @PayloadRoot(namespace = SOAP_NAMESPACE,localPart = "idCheckRequest")
    @ResponsePayload
    public idCheckResponseDTO checkId(@RequestPayload idCheckRequestDTO idCheckRequestDTO) throws IOException {
        //code
    }
}