How are the parameters sorted？

[yangyao]

<?xml version="1.0"?>
<methodCall>
<methodName>login</methodName>
<params>
    <param><value><string><![CDATA[username]]></string></value></param>
    <param><value><string><![CDATA[apiKey]]></string></value></param>
</params>
</methodCall>

This request contains two string value.

    err = rpcClient.Call("login", &struct {
        UserName string
        ApiKey   string
    }{
        UserName: "username",
        ApiKey:   "apiKey",
    }, nil)

i got

<methodCall>
<methodName>login</methodName>
<params>
    <param><value><string>apiKey</string></value></param>
    <param><value><string>username</string></value></param>
</params>
</methodCall>

username should be the first param .