REST driver.

The filter content looks fine, is valid XML and such.
However driver refuses to start with the filter as-is

Replacing the filter with an empty one, the driver starts up just fine.

Anyone seen this before. Is it a quirk particular to the REST driver?
I recall that the bidir eDir driver had some driver filter oddities but
that occurred far later during startup (as the shim requests the entire
driver filter blob rather than just relying on init-params.

Here, we don't even get to init-params. It loads only the following
before borking out.

Acme :Reading driver information from the
\IDV-T-TREE\IDV\System\DriverSet1\Acme object.
Acme :Reading named passwords list.
Acme :Named passwords:
Acme : Name: pubAuthPwd
Acme : Name: sub-password
Acme : Name: subAuthPwd-1
Acme :Reading XML attribute
vnd.nds.stream://IDV-T-TREE/IDV/System/DriverSet1/Acme#DirXML-EngineControlValues.
Acme :Reading XML attribute
vnd.nds.stream://IDV-T-TREE/IDV/System/DriverSet1#DirXML-ConfigValues.
Acme :Reading XML attribute
vnd.nds.stream://IDV-T-TREE/IDV/System/DriverSet1/Acme#DirXML-ConfigValues.
Acme :Global Configuration Values:
Acme : Name: enable-password-subscribe Value: false
Acme : Name: enable-password-publish Value: true
Acme : Name: publish-password-to-nds Value: false
Acme : Name: publish-password-to-dp Value: true
Acme : Name: enforce-password-policy Value: false
Acme : Name: reset-external-password-on-failure Value: false
Acme : Name: notify-user-on-password-dist-failure Value: false
<snip>
Acme : Name: dirxml.auto.treename Value: IDV-T-TREE
Acme : Name: dirxml.auto.driverdn Value:
\IDV-T-TREE\IDV\System\DriverSet1\Acme
Acme : Name: dirxml.auto.driverguid Value: {blah}
Acme : Name: dirxml.auto.localserverdn Value:
CN=T-IDM-NDS,OU=Servers,OU=System,O=IDV
Acme :Reading XML attribute
vnd.nds.stream://IDV-T-TREE/IDV/System/DriverSet1/Acme#DirXML-ReciprocalAttrMap.
Acme :Loaded reciprocal attribute map
Acme :

Acme :Reading XML attribute
vnd.nds.stream://IDV-T-TREE/IDV/System/DriverSet1/Acme#DirXML-PersistentData.
Acme :Loaded persistent data
Acme :
<persistent-data>
<snip>
</persistent-data>
Acme :Found subscriber IDV\System\DriverSet1\Acme\Subscriber.
Acme :Found publisher IDV\System\DriverSet1\Acme\Publisher.
Acme :Reading XML attribute
vnd.nds.stream://IDV-T-TREE/IDV/System/DriverSet1/Acme#DirXML-DriverFilter.
Acme :Writing XML attribute
vnd.nds.stream://IDV-T-TREE/IDV/System/DriverSet1/Acme#DirXML-PersistentData.