Can query relationship by formal attribute

I have a custom relationship that only has @AttributeProperty values. I am querying based on an AttributeParameter and not getting any results back. I don't know if this is a bug or something I'm doing wrong.

testCreate2() is the test

https://github.com/patriot1burke/picketlink/blob/master/modules/idm/tests/src/test/java/org/picketlink/test/idm/relationship/CustomRelationshipTestCase.java

https://github.com/patriot1burke/picketlink/blob/master/modules/idm/tests/src/test/java/org/picketlink/test/idm/relationship/RequiredCredentialRelationship.java