我在测试外部联系人免验证添加成员事件时，通过配置客户联系功能获得二维码，然后用其他的微信扫二维码时，自动通过可以聊天，触发的回调事件参数是 [代码]<xml>[代码][代码] [代码][代码] [代码][代码]<ToUserName>[代码][代码]<![CDATA[toUser]]>[代码][代码]</ToUserName>[代码][代码] [代码][代码]<AgentID>[代码][代码]<![CDATA[toAgentID]]>[代码][代码]</AgentID>[代码][代码] [代码][代码]<Encrypt>[代码][代码]<![CDATA[msg_encrypt]]>[代码][代码]</Encrypt>[代码][代码]</xml>[代码]而不是文档里的 [代码]<xml>[代码][代码] [代码][代码]<ToUserName>[代码][代码]<![CDATA[toUser]]>[代码][代码]</ToUserName>[代码][代码] [代码][代码]<FromUserName>[代码][代码]<![CDATA[sys]]>[代码][代码]</FromUserName>[代码][代码] [代码][代码] [代码][代码]<CreateTime>[代码][代码]1403610513[代码][代码]</CreateTime>[代码][代码] [代码][代码]<MsgType>[代码][代码]<![CDATA[event]]>[代码][代码]</MsgType>[代码][代码] [代码][代码]<Event>[代码][代码]<![CDATA[change_external_contact]]>[代码][代码]</Event>[代码][代码] [代码][代码]<ChangeType>[代码][代码]<![CDATA[add_half_external_contact]]>[代码][代码]</ChangeType>[代码][代码] [代码][代码]<UserID>[代码][代码]<![CDATA[zhangsan]]>[代码][代码]</UserID>[代码][代码] [代码][代码]<ExternalUserID>[代码][代码]<![CDATA[woAJ2GCAAAXtWyujaWJHDDGi0mACAAAA]]>[代码][代码]</ExternalUserID>[代码][代码] [代码][代码]<State>[代码][代码]<![CDATA[teststate]]>[代码][代码]</State>[代码][代码] [代码][代码]<WelcomeCode>[代码][代码]<![CDATA[WELCOMECODE]]>[代码][代码]</WelcomeCode>[代码][代码]</xml>[代码]这个是怎么回事，我要怎么办才能拿到下面的参数？