ModelAttribute方法在没有提供的模型的方法上执行

Question

我有：

@ControllerAdvice(assignableTypes = CommentController.class)
public class Test {

    private final ThreadServices threadServices;
    private final UserServices userServices;

    @Autowired
    public Test(ThreadServices threadServices, UserServices userServices) {
        this.threadServices = threadServices;
        this.userServices = userServices;
    }

    @ModelAttribute
    public CommentCreateBindingModel fill(CommentCreateBindingModel bindingModel, @PathVariable String threadId, Principal principal){
        UserServiceModel creator = this.userServices.findUserByUsername(principal.getName());
        ThreadServiceModel thread = this.threadServices.findById(threadId);

        bindingModel.setCreator(creator);
        bindingModel.setThread(thread);

        return bindingModel;
    }

    }

和控制器：

@Controller
public class CommentController extends BaseController {

    private final CommentServices commentServices;
    private final ModelMapper modelMapper;
    private final ThreadServices threadServices;

    @Autowired
    public CommentController(CommentServices commentServices, ModelMapper modelMapper, ThreadServices threadServices) {
        this.commentServices = commentServices;
        this.modelMapper = modelMapper;
        this.threadServices = threadServices;
    }


    @PreAuthorize("hasAuthority('MODERATOR') or @commentServicesImp.findById(#commentId).creator.username.equals(principal.username)")
    @PostMapping(URLConstants.COMMENT_DELETE_POST)
    public String proceedCommentDeletion(@PathVariable String commentId) {

        CommentServiceModel commentServiceModel = this.commentServices.findById(commentId);
        this.commentServices.delete(commentId);

        String threadId = commentServiceModel.getThread().getId();
        String redirectUrl = URLConstants.THREAD_READ_GET.replace("{threadId}", threadId);
        return super.redirect(redirectUrl);
    }

    @PreAuthorize("isAuthenticated()")
    @PostMapping(value = URLConstants.THREAD_CREATE_COMMENT_POST, produces = "application/json")
    @ResponseBody
    public String proceedCommentCreation(@PathVariable String threadId,
                                         @Valid @ModelAttribute CommentCreateBindingModel commentCreateBindingModel,
                                         BindingResult bindingResult) {

        if(bindingResult.hasErrors()){
            return new Gson().toJson(false);
        }

        this.commentServices.create(commentCreateBindingModel);

        return new Gson().toJson(true);
    }

    }

问题在于，填充方法每次在我的控制器中被调用时都会执行，这会导致异常。我希望仅当方法包含CommentCreateBindingModel

时才执行方法填充