Java SpringBoot：在条件{Variable}.isBlank{Variable}.isEmpty不起作用的情况下进行路径变量验证

我有一个控制器，我想在其中验证不能为空的Path Variable.例如，http://localhost:8080/api/details/expired-timeoff/，其中我想要验证此路径中‘/’后面的PATH变量.

我这里有我的控制器，我想在上面抛出带有错误消息的异常.

@RestController
@CrossOrigin("*")
@RequestMapping("/api/details")
public class DetailsController {
    @Autowired
    DetailsService detailsService;
    
    @Autowired
    OvertimeService overtimeService;
        
    // TESTING HERE!!!!
    @GetMapping("/expired-timeoff/{empNo}")
    public List<Details> getExpiredTimeOffBalancesByUser(@PathVariable String empNo) {

        if (empNo.isBlank() || empNo.isEmpty() || empNo.trim().equals("a")) {
            throw new InvalidArgumentException("Error Message");
        }
        return detailsService.findExpiredTimeOffBalancesByCreatedBy(empNo);
    }


}

同时，当我从"http://localhost:8080/api/details/datared-timeoff/a"获取时，我可以输入条件并捕获InvalidArgumentException消息 Successfully catch my exception

当我从"http://localhost:8080/api/details/expired-timeoff/"，获取信息时，它只会返回默认的白色标签404错误 Exception not catched个

我对它做了一些研究，声明Path Variable不能为空，但如果用户不小心将Path变量设置为"空"，我该怎么做才能提示InvalidArgumentException？

以下是我的@RestControllerAdvise文件

package com.sicmsb.timeofftracker.controller.Advice;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.client.HttpClientErrorException;

import com.sicmsb.timeofftracker.exceptions.ResourceNotFoundException;
import com.sicmsb.timeofftracker.exceptions.InvalidArgumentException;

@RestControllerAdvice
public class RequestExceptionHandler {
    @ResponseStatus(HttpStatus.NOT_FOUND) //404
    @ExceptionHandler(ResourceNotFoundException.class)
    public String notFound(Exception e) {
        //e.printStackTrace();
        return e.getMessage();
    }
    
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR) //500
    @ExceptionHandler({RuntimeException.class, Exception.class})
    public String internalError(Exception e) {
        e.printStackTrace();
        return "error/internal_error";
    }
    
    @ResponseStatus(HttpStatus.BAD_REQUEST) //400
    @ExceptionHandler({InvalidArgumentException.class})
    public String badRequest(Exception e) {
        return e.getMessage();
    }
}

更新:似乎我可以处理这样的错误.有没有办法让我只使用一个函数来处理所有的问题？try 了String.utils(empNo)和empNo==null，仍然没有进入条件.

// Handles cases where empNo is NOT provided
@GetMapping("/expired-timeoff/")
public List<Details> getExpiredTimeOffBalancesByUser() {
    throw new InvalidArgumentException("Error Message2");
}