php传xml格式调用webservice接口，java接收不到参数

<?php
//本人亲身经历 为解决php开发对接java webservice 返回为null的问题,特写此博客,希望大家别入坑!
header("content-type:text/html;charset=utf-8");

try {
　　 //必须开启php soap扩展不开启,否则调用失败
    $url = "********";//需调用的url
    $client = new SoapClient($url);
　　//打印下是否出现对方的接口名字
    var_dump($client->__getFunctions());
    print("<br/>");
    var_dump($client->__getTypes());
    print("<br/>");die;
    $xml = "<root>
<item>
<orderNum>201907161515216588625</orderNum>
<buyerAccount>caigou01</buyerAccount>
<ecPlatformAccount>ydc002</ecPlatformAccount>
<orderStatus>1</orderStatus>
<orderAmount>9856.56</orderAmount>
<orderTime>2019-07-23 12:56:12</orderTime>
<articles>
<articleNum>00101</articleNum>
<articleName>笔记本</articleName>
<brand>华为</brand>
<modelNum>TG-879564123</modelNum>
<unitPrice>1000.0</unitPrice>
<articleQuantity>10</articleQuantity>
<articleUrl>http://www.baidu.com</articleUrl>
</articles>
<articles>
<articleNum>00102</articleNum>
<articleName>打印机</articleName>
<brand>得力</brand>
<modelNum>DY-4569856</modelNum>
<unitPrice>2365.12</unitPrice>
<articleQuantity>2</articleQuantity>
<articleUrl>http://www.baidu.com</articleUrl>
</articles>
</item>
</root>";
　　//必须key是 'arg0';
    $ParamData=array('arg0'=>$xml);
　　//调用对方的接口方法并传过去
    $return = $client->pushOrderData($ParamData);
    var_dump($return);die;
} catch (SOAPFault $e) {
    print $e;
}
?>