Spring在API响应中返回java对象时添加额外的键

public class ExtraData {
    private Map<String, Object> extraFields = new HashMap<>();

    @JsonAnyGetter
    public Map<String, Object> getExtraFields() {
        return extraFields;
    }

    public void addExtraField(String key, Object value) {
        extraFields.put(key, value);
    }
}

public class MyResponse {
    private String message;
    private ExtraData extraData;

    // getters and setters

    public void addExtraField(String key, Object value) {
        if (extraData == null) {
            extraData = new ExtraData();
        }
        extraData.addExtraField(key, value);
    }
}

@RestController
public class MyController {
    @GetMapping("/api/myendpoint")
    public MyResponse getMyResponse() {
        MyResponse response = new MyResponse();
        response.setMessage("Hello World");
        response.addExtraField("extraKey", "extraValue");
        return response;
    }
}