MybatisPlus出现Error attempting to get column ‘xxx字段‘ from result set异常解决

@Data
@EqualsAndHashCode
@TableName("demo")

public class Demo implements Serializable {

    private static final long serialVersionUID = 1L;

    /**
     * 主键
     */
    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;

    /**
     * 身份证号
     */
    @TableField("id_card")
    private String idCard;

    /**
     * 受试者姓名
     */
    @TableField("`name`")
    private String name;

    /**
     * 联系电话
     */
    @TableField("phone")
    private String phone;

    /**
     * 入组时间
     */
    @TableField("join_time")
    private Date joinTime;

    /**
     * 状态：已入组、已出组、已移除
     */
    @TableField("state")
    private DemoStateEnum state;

    /**
     * 最近一次操作的用户
     */
    @TableField("last_user")
    private String lastUser;

    /**
     * 关联项目ID
     */
    @TableField("project_id")
    private Integer projectId;

    /**
     * 最后一次操作时间
     */
    @TableField("last_update")
    private Date lastUpdate;

    public static Demo builder(){
        return new Demo();
    }
}

public enum DemoStateEnum {

    JOINED("已入组"),
    OUTED("已出组"),
    REMOVED("已移除");
    
    /**
     * 注意这个 @EnumValue注解一定要加上，否则SpringBoot启动都会报错，具体原因是因为MybatisePlus实现了根据这个注解表示实体属性自动枚举类型转换。如果找不到就会报错。
     */
    @EnumValue
    private String state;

    DemoStateEnum(String state){
       this.state = state;
    }
    
    /**
     * @JSONField这个注解解决alibaba.fastjson序列化是枚举显示的索引的值，而我们想要的显示是具体的值：已入组、已出组、已移除等。
     */
    @JSONField
    public String getState() {
        return state;
    }

    @Override
    public String toString() {
        return "DemoStateEnum{" +
                "state='" + state + '\'' +
                '}';
    }
}

CREATE TABLE `demo` (
  `id` int NOT NULL AUTO_INCREMENT COMMENT '主键',
  `id_card` varchar(60) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '' COMMENT '身份证号',
  `name` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL DEFAULT '' COMMENT '受试者姓名',
  `phone` varchar(13) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT '' COMMENT '联系电话',
  `join_time` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '入组时间',
  `state` enum('已入组','已出组','已移除') CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '状态：已入组、已出组、已移除',
  `last_user` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '最近一次操作的用户',
  `project_id` int NOT NULL COMMENT '关联项目ID',
  `last_update` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '最后一次操作时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci COMMENT='枚举测试表';

@SpringBootTest
public class DemoTest {

    @Autowired
    private DemoMapper deemoMapper;
    
    //查询所有demo数据
    @Test
    public void querySubject() throws JsonProcessingException {
        List<Demo> demos = deemoMapper.selectList(null);
        System.err.println(JSON.toJSONString(demos));
    }

}

# 根据上图细看这句话
Caused by: java.sql.SQLFeatureNotSupportedException
	at com.alibaba.druid.pool.DruidPooledResultSet.getObject(DruidPooledResultSet.java:1771)

public <T> T getObject(String columnLabel, Class<T> type) throws SQLException {
  throw new SQLFeatureNotSupportedException();
}

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid-spring-boot-starter</artifactId>
    <version>1.1.21</version>
</dependency>

public <T> T getObject(String columnLabel, Class<T> type) throws SQLException {
  try {
      // 正常调用JDBC中的ResultSet了，所以可以正常获取数据，不再出现那个异常了。
      return this.rs.getObject(columnLabel, type);
  } catch (Throwable var4) {
      throw this.checkException(var4);
  }
}

    @JSONField
    public String getState() {
        return state;
    }