Java：为何事务的实际执行结果与预期不符 报错

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@Controller @EnableAutoConfiguration public class SampleController {

@Autowired
private WeiboRepository weiboRepository;

@Autowired
private TwitterRepository twitterRepository;

@RequestMapping("/postWeibo")
@ResponseBody
public void postWeibo() {
    Weibo weibo = new Weibo("Weibo");
    weiboRepository.save(weibo);
    postTwitter();
}

@Transactional(propagation = Propagation.REQUIRED, rollbackFor = Exception.class)
public void postTwitter() {
    Twitter twitter = new Twitter("Twitter");
    twitterRepository.save(twitter);
    throw new RuntimeException();
}

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

}

代码逻辑：添加一条微博的同时添加一条推特，postTwitter手动抛出异常模拟回滚
预期结果：Twitter表由于抛出异常造成回滚什么都没有添加，但Weibo表正常添加
实际结果：虽抛出异常但Twitter、Weibo表均正常添加

请问我已经设置了@Transactional，事务级别为REQUIRED表明postTwitter会单独开启新的事务，为何实际执行结果与预期不符合呢？