我使用Postman发送一个带有一些值的POST请求（我放了两个字符串，一个是用户名，另一个是邮件），但所有数据都保存到第一列（“用户名”）。我做错了什么？

我试过了。

{
    "username": "mm46676",
    "mail": "[email protected]"
}

字符串
我希望mm46676保存在用户名列中，email protected(https://stackoverflow.com/cdn-cgi/l/email-protection)保存在邮件列中。我使用H2控制台查看它是如何保存在db.

中的
EmployeeController.java

import com.incompatibleTypes.plancation.plancationapp.model.Employee;
import com.incompatibleTypes.plancation.plancationapp.repository.EmployeeRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.*;
@Controller
@RequestMapping(path = "/employee")
public class EmployeeController {
    private final EmployeeRepository employeeRepository;
    public EmployeeController(EmployeeRepository employeeRepository) {
        this.employeeRepository = employeeRepository;
    }
    @GetMapping("/all")
    public @ResponseBody Iterable<Employee> showAllEmployees(){
        return employeeRepository.findAll();
    }
    @PostMapping(path = "/add")
    public @ResponseBody String addNewEmployee (@RequestBody String username, String mail){
        Employee employee = new Employee();
        employee.setUsername(username);
        employee.setMail(mail);
        employeeRepository.save(employee);
        return "Employee Saved!";
    }
}

型
员工模型（如果它能以任何方式提供帮助）

package com.incompatibleTypes.plancation.plancationapp.model;
import jakarta.persistence.*;
import lombok.Data;
import java.time.LocalDateTime;
import java.util.HashSet;
import java.util.Set;
import java.util.UUID;
@Data
@Entity
@Table(name = "employee")
public class Employee {
    @Id
    @GeneratedValue(strategy = GenerationType.UUID)
    private UUID id;
    private Role role;
    @Column(name = "username")
    private String username;
    @Column(name = "mail")
    private String mail;
    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "department_id")
    private Department department;
    @ManyToOne
    @JoinColumn(name = "minimal_vacation_day_id") 
    private VacationDay minimalVacationDay;
    @ManyToMany
    @JoinTable(
            name = "employee_bonusvacdays",
            joinColumns = @JoinColumn(name = "bonus_vacation_day_id"),
            inverseJoinColumns = @JoinColumn(name = "employee_id")
    )
    private Set<BonusVacationDay> bonusVacationDays = new HashSet<>();
    private LocalDateTime dateEmployed;
}

型