java.lang.IllegalStateException：无法转换类型的值

Question

[当我将SubmitState设置为ModelAndView的属性时，我遇到以下异常：

java.lang.IllegalStateException: Cannot convert value of type 'example.package.SubmitState' to required type 'java.lang.String': no matching editors or conversion strategy found
    at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:262)
    at org.springframework.beans.TypeConverterSupport.convertIfNecessary(TypeConverterSupport.java:73)

设置方法：model.addAttribute(someField, submitState);

设置完成后，我尝试重定向到页面，但出现异常。

SubmitState：

public class SubmitState implements Serializable {

    private String msgClass;

    private String msgKey;

    public void setMsgClass(String msgClass) {
        this.msgClass = msgClass;
    }

    public String getMsgClass() {
        return msgClass;
    }

    public void setMsgKey(String msgKey) {
        this.msgKey = msgKey;
    }

    public String getMsgKey() {
        return msgKey;
    }
}

Answer 1

model.addAttribute("some-key", submitState);