feign开启sentinel报错Cannot invoke “org.springframework.cloud.openfeign.FeignClientFactoryBean.getFallback()”

1.场景

启动服务Application报错：

Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.cloud.openfeign.FeignClientFactoryBean.getFallback()" because "feignClientFactoryBean" is null
    at com.alibaba.cloud.sentinel.feign.SentinelFeign$Builder$1.create(SentinelFeign.java:93) ~[spring-cloud-starter-alibaba-sentinel-2022.0.0.0-RC1.jar:2022.0.0.0-RC1]
    at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:59) ~[feign-core-12.1.jar:na]
    at feign.ReflectiveFeign.newInstance(ReflectiveFeign.java:50) ~[feign-core-12.1.jar:na]
    at feign.Feign$Builder.target(Feign.java:197) ~[feign-core-12.1.jar:na]
    at org.springframework.cloud.openfeign.DefaultTargeter.target(DefaultTargeter.java:30) ~[spring-cloud-openfeign-core-4.0.2.jar:4.0.2]
    at org.springframework.cloud.openfeign.FeignClientFactoryBean.loadBalance(FeignClientFactoryBean.java:398) ~[spring-cloud-openfeign-core-4.0.2.jar:4.0.2]
    at org.springframework.cloud.openfeign.FeignClientFactoryBean.getTarget(FeignClientFactoryBean.java:446) ~[spring-cloud-openfeign-core-4.0.2.jar:4.0.2]
    at org.springframework.cloud.openfeign.FeignClientFactoryBean.getObject(FeignClientFactoryBean.java:421) ~[spring-cloud-openfeign-core-4.0.2.jar:4.0.2]
    at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:148) ~[spring-beans-6.0.7.jar:6.0.7]
    ... 31 common frames omitted

环境：

springboot版本：3.0.5
springcloud版本：2022.0.2
spring-cloud-alibaba版本：2022.0.0.0-RC1

相关代码：

order-service模块：

@MapperScan("cn.itcast.order.mapper")
@SpringBootApplication
        // (scanBasePackages = "cn.itcast.feign")
@EnableFeignClients(clients = UserClient.class)
        // ,defaultConfiguration = UserFeignConfig.class)
public class OrderApplication {

    public static void main(String[] args) {
        SpringApplication.run(OrderApplication.class, args);
    }


    @Bean
    @LoadBalanced
    public RestTemplate restTemplate() {
        // todo 据说官方推荐RestTemplateBuilder
        return new RestTemplate();
    }

feign:
  sentinel:
    enabled: true

feign-api模块：

@FeignClient(value = "user-service", fallbackFactory = UserClientFallbackFactory.class,configuration = UserFeignConfig.class)
public interface UserClient {
    @GetMapping("/user/{id}")
    Result findById(@PathVariable("id") Long id);
}

@Slf4j
public class UserClientFallbackFactory implements FallbackFactory<UserClient> {
    @Override
    public UserClient create(Throwable cause) {
        //编写失败降级的处理逻辑
        return new UserClient() {
            @Override
            public Result findById(Long id) {
                log.error("查询用户异常",cause);
                return new Result(Code.GET_ERR,new User());
            }
        };
    }
}

public class UserFeignConfig {
    //定义日志输出级别
    @Bean
    public Logger.Level feignLoggerLevel(){
        return Logger.Level.BASIC;
    }

    @Bean
    public UserClientFallbackFactory userClientFallbackFactory(){
        return new UserClientFallbackFactory();
    }

2.分析

一开始以为是@FeignClient注解和@EnableFeignClient注解的configuration和defaultConfiguration注解无效的问题，导致userClientFallbackFactory没有被成功创建。
打断点debug之后发现这个Bean已经被创建了，结合报错信息FeignClientFactoryBean是null，说明不是注解的问题。
跑了下黑马的示例代码发现没有任何问题，于是把黑马代码环境换成我的环境，错误重现了。那就说明是环境问题。
搜了下发现确实：完全一样的错误

3.解决方法

根据官方回答，解决方法有两种：
方法1：

只要在配置文件里开启懒加载即可

spring:
  cloud:
    openfeign:
      lazy-attributes-resolution: true

方法2：
升级spring-cloud-alibaba依赖版本

 <dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-alibaba-dependencies</artifactId>
    <!--<version>2022.0.0.0-RC1</version>-->
    <version>2022.0.0.0-RC2</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>

笑鼠 明明是bug，非要写在feature里