Force SP to sign SOAP messages

[David Sommer]

> That's a matter of metadata in some sense; if you only want artifact support, you'd update your metadata and edit protocols.xml to adjust the auto-wiring by commenting out the bindings you don't want.
This worked, but didn't fix the issue, unfortunately. I suspect that the
sp might be unable to sign the message unsigned and simply sends it
unsigned. However the logs show no such error, even when raising
log4j.category.XMLTooling.Signature.Debugger to DEBUG. Is there another
way to determine if the SP fails to sign messages or to even force the
sp to not send messages at all when failing to sign them?