[alibaba/fastjson]当bean中的属性大小写和json数据中不一致时，反序列化后序列化导致属性数据丢失

当bean中的属性大小写和json数据中不一致时，反序列化后序列化导致属性数据丢失，测试代码如下

public static void main(String[] args) {
    String s = "{\"USER_NAME\": \"faster\"}";
    User user = JSON.parseObject(s, User.class);
    System.out.println("===>" + user.getUsername());
    System.out.println("===>" + user.getUser_name());
    System.out.println(JSON.toJSONString(user));
}

public static class User {
    private String user_name;
    private String username;
    public String getUser_name() {
        return user_name;
    }
    public void setUser_name(String user_name) {
        this.user_name = user_name;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
}

测试结果为如下

===>faster
===>null
{"username":"faster"}

这种情况应该如何解决