xmlns:xml is secretly added in outgoing SOAP call

Hi, I currently have a project in version 5.21.4 and experience an issue with outgoing webservice calls. I am consuming a third party webservice and mendix is adding --xmlns:xml="http://www.w3.org/XML/1998/namespace"-- to the outgoing webservice call. Funny thing is that in the modeler logging this extra namespace declaration is not visible, but when capturing the message with wireshark, it is.

The third party is returning an syntax error due to this extra namespace. I don't know if the declaration is specifically wrong, but does someone understand why this extra declaration is made and why this is not visible in the logging?

Mendix modeler log shows that the outgoing Soap request is:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <soapenv:Header>
        <ns1:Authenticate xmlns:ns1="http://www.loyaltyinabox.com/giftcard_5_7/" xsi:type="ns1:Authenticate">
            <ns1:UserName>xxxx</ns1:UserName>
            <ns1:Password>xxxx</ns1:Password>
        </ns1:Authenticate>
    </soapenv:Header>
    <soapenv:Body>
        <ns1:BlockCard xmlns:ns1="http://www.loyaltyinabox.com/giftcard_5_7/">
            <ns1:CardId>xxxx</ns1:CardId>
        </ns1:BlockCard>
    </soapenv:Body>
</soapenv:Envelope>

While catching the ougoing message with Wireshark it shows this:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <soapenv:Header>
        <ns1:Authenticate xmlns:ns1="http://www.loyaltyinabox.com/giftcard_5_7/" xsi:type="ns1:Authenticate">
            <ns1:UserName>xxxx</ns1:UserName>
            <ns1:Password>xxxx</ns1:Password>
        </ns1:Authenticate>
    </soapenv:Header>
    <soapenv:Body>
        <ns1:BlockCard xmlns:ns1="http://www.loyaltyinabox.com/giftcard_5_7/"
                        xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
                        xmlns:xml="http://www.w3.org/XML/1998/namespace"
                        xmlns:xsd="http://www.w3.org/2001/XMLSchema"
                        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
            <ns1:CardId>xxxx</ns1:CardId>
        </ns1:BlockCard>
    </soapenv:Body>
</soapenv:Envelope>

In the block card operation, extra declarations are made. The one that is causing the issue is: xmlns:xml

The used WSDL can be found here: http://demo.luntronics.com/liabwebservice/giftcard57.asmx?WSDL

Please note that there is also an 'AnyAttribute' used. Mendix already states that it is not supported during WSDL import but apart from that it seems to be working normally.