用友 【实名认证API】使用过程中遇到“Requied parameter can not be null"问题

在学习使用用友平台下实名认证API(该API的商品页面
)的过程中，发现不管怎么写请求参数、不管是传参、直接赋值还是其他方式传入请求参数，请求API后的返回值都说idNumber字段为空：
{'status':'-1', 'msg':'errcode:300017, errormsg: Requied parameter can not be null: idNumber'}

问客服那边也没有任何回应。请求大佬们指点一下错误所在或者排查的方向

————————————————————

源码如下

header('Content-type:text/html;charset=utf-8');
    //配置您申请的appkey
    $apicode = "略";

    $url = "https://api.yonyoucloud.com/apis/dst/matchIdentity/matchIdentity";

    $method = "POST";

    $params = array(
        //"idNumber" => $_POST['ture_name2'],
        //"userName" => $_POST['ture_name1'],
        "idNumber" => "156103191101110000",
        "userName" => "徐同学",
    );

    $header = array();
    $header[] = "apicode:".$apicode;
    $header[] = "content-type:application/json";
    $header[] = "Content-Type:application/json";

    echo file_put_contents("test0.txt",$header);

//这里是调用商品界面中的示例方法linkcurl
    $content = linkcurl($url,$method,$params,$header);
    echo file_put_contents("test.txt",$content);
    $result = json_decode($content,true);
    if($result){
        if($result['error_code']=='0'){
            echo file_put_contents("test1.txt","text1");

        }else{
            $custom_field_errors[] = array('custom_field_inproper_format', array('notify_announcements'));
            echo file_put_contents("test2.txt","text2");
        }
    }else{
        $custom_field_errors[] = array('custom_field_inproper_format', array('notify_announcements'));
        echo file_put_contents("test3.txt","text3");
    }

https://www.csdn.net/gather_2f/Ntzagg2sMTgxMi1ibG9n.html