I managed to find (and fix) a bug where it was possible to get attribute requests that had more attributes in AttributeHandleSet than should and they had values of 0.

This happens when two federates own attributes of one object and third federate requests ownerships for those attributes (in a way that one request contains attributes owned by both other federates).

Actual issue was in libCERTI/ObjectClass.cc ObjectClass::sendToOwners() function. It sets attribute size of answer to count of all attributes, but then it fills (correctly) handles that federate owns and that count is less than count of all attributes if some of the attributes are owned by other federate.

Fix is simple. Put this line
answer.setAttributesSize(index);
before sendToFederate() in that sendToOwners() function.

This problem can probably happen in other ownership related functions too as sendToOwners is used in them.

This similar thing is done in numerous places in code, but apparently forgotten here.