$ godoc encoding/xml | grep 'xml\.'
    - the value of the XMLName field of type xml.Name
    * If the struct has a field named XMLName of type xml.Name,
    Unmarshal maps an XML element to an xml.Name by recording the element
    Decode works like xml.Unmarshal, except it reads the decoder stream to
    DecodeElement works like xml.Unmarshal except that it takes a pointer to
$

It appears to be breaking the convention for no good reason. It needs s/xml\.//