我正在学习java的spring Boot 这是一个通用的模式。现在我发现了一个错误，我一直在寻找，但不能找到问题的症结。
当我在postman中执行GET时，它显示错误500：
“不是实体：类com.示例.服务器端.模型.基础实体.基础实体;嵌套的异常是java.lang.IllegalArgumentException：非实体：类com.示例.服务器端.模型.基础实体.基础实体”，
我已经检查了几次，也看过类似的问题，但找不到答案。
这是我在BaseEntity、GenericRepository、区域服务和区域控制器上的代码。
模型基本实体'

package com.example.serverside.models.baseEntity;

import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
@MappedSuperclass
public class BaseEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

}

模型区域

package com.example.serverside.models;

import java.util.List;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import com.example.serverside.models.baseEntity.BaseEntity;
import com.fasterxml.jackson.annotation.JsonProperty;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Entity
@Table(name="region")
public class Region extends BaseEntity {

    @Column( nullable = false)
    private String name;

    @JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
    @OneToMany(mappedBy = "region", cascade = CascadeType.ALL)
    private List<Country> countries;

}

通用存储库

package com.example.serverside.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import com.example.serverside.models.baseEntity.BaseEntity;

@Repository
public interface GenericRepository<T extends BaseEntity> extends JpaRepository<T,Long> {

}

区域服务

package com.example.serverside.services;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.example.serverside.models.Region;
import com.example.serverside.repository.GenericRepository;

@Service
public class RegionService {

    private GenericRepository<Region> regionRepository;

    @Autowired
    public RegionService(GenericRepository<Region> regionRepository) {
        this.regionRepository = regionRepository;
    }

    // findAll
    public List<Region> findAll(){
        return regionRepository.findAll();
    }

}

区域控制器

package com.example.serverside.controllers;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.example.serverside.models.Region;
import com.example.serverside.services.RegionService;

import lombok.AllArgsConstructor;

@RestController
@RequestMapping("/api/v1/region")
public class RegionController{

    private RegionService regionService;

    @Autowired
    public RegionController(RegionService regionService) {
        this.regionService = regionService;
    }

    @GetMapping
    public ResponseEntity<List<Region>> findAll() {
        return new ResponseEntity(regionService.findAll(), HttpStatus.OK);
    }

}

`
我希望找到我问题的症结所在，以及如何解决它