Right now all of the sets associated with concept except set members and answers are returned in both the default and full representations. The set boolean is also included.
I don't believe either set members or answers should be sub-resources because their type is concept. Rather, I believe they should be presented as reference lists (that is, a list of set members or answers in the reference representation). I am willing to see both be present only in the full representation, so long as there is a hasAnswers boolean in the default representation. This would have to be a calculated field in Concept.hbm.xml with a getter in Concept.java.
These changes are needed for the JSS project, so if we don't want to make and backport any changes to Concept, I suggest that we add both reference lists to both the default and full representations.