Wie entmarshaliere ich XML direkt in eine Go-Map?

<classAccesses>
    <apexClass>AccountRelationUtility</apexClass>
    <enabled>true</enabled>
</classAccesses>

map[string]string{
    "ApexClass": "enabled"
}

type classAccessesMap struct {
    m map[string]string
}

func (c *classAccessesMap) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
    c.m = map[string]string{}

    key := ""
    val := ""

    for {
        t, _ := d.Token()
        switch tt := t.(type) {

        // TODO: ...

        case xml.StartElement:
            fmt.Println(">", tt)

        case xml.EndElement:
            fmt.Println("<", tt)
            if tt.Name == start.Name {
                return nil
            }

            if tt.Name.Local == "enabled" {
                c.m[key] = val
            }
        }
    }
}

var classAccesses classAccessesMap
if err := xml.Unmarshal(data, &classAccesses); err != nil {
    // Handle error
}

fmt.Println(classAccesses.m)