follow-up.xml

<followUpRequest
        xmlns="http://efti.fi/v0/platform"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://efti.fi/v0/platform">
    <message>Identifiers missing</message>
    <attachment mimeType="text/plain" fileName="foo.txt">
        SGVsbG8gV29ybGQh
    </attachment>
</followUpRequest>