Spring验证:使用两个验证器时获取“验证器的无效目标”

控制器代码:

@Autowired
private SessionValidator sessionValidator;

@Autowired
private ChannelValidator channelValidator;

@InitBinder
public void initBinder(WebDataBinder binder){
    binder.addValidators(sessionValidator, channelValidator);
}

@RequestMapping(method = RequestMethod.GET)
public UserInfo findBySession(
        @Valid @ModelAttribute Session session,
        @Valid @ModelAttribute Channel channel){
    //...
}

会话验证程序:

@Component
public class SessionValidator implements Validator {

    @Override
    public boolean supports(Class<?> aClass){
        return Session.class.equals(aClass);
    }

    @Override
    public void validate(Object o, Errors errors){
        //...
    }
}

通道验证器:

@Component
public class ChannelValidator implements Validator {

    @Override
    public boolean supports(Class<?> aClass){
        return Channel.class.equals(aClass);
    }

    @Override
    public void validate(Object o, Errors errors){
        //...
    }
}

我在调用控制器时收到以下异常:

Caused by: java.lang.IllegalStateException: Invalid target for Validator [com.almundo.p13n.dna.validators.ChannelValidator@4e642ee1]: Session(null, null)

有人知道怎么解决吗?提前谢谢!