Cannot find groups having a particular attribute value

We are attempting to use GroupAttributeFilter to find groups having a particular attribute value. The code looks like this:

GrouperSession gs = <get session>
GroupAttributeFilter gaf = new GroupAttributeFilter(
     "bath:provisionClass", "groupmanager-groups",
     StemFinder.findRootStem(gs));
Set<Group> ggroups = gaf.getResults(gs);

No results are returned. This appears to be because in Hib3GropDAO.findAllByApproximateAttrHelper the following code...

String attributePrefix = legacyAttributeStemName + ":" + legacyAttributePrefix; if (attr.startsWith(attributePrefix)) {
     byHql.setString("attributeName",  attr); } else {
     byHql.setString("attributeName",  attributePrefix + attr); }

...is actually setting the name of the attribute being examined to:

etc:legacy:attribute:legacyAttribute_bath:provisionClass

Are we missing something, or is there a bug here?

We are using version 2.3.0 of the grouper Maven artifact, but this code seems unchanged in the latest updates to GitHub.