AttributeSet model only contains a single field (at least it did until !1054 (merged)) and has a one-to-one relation to
Subject. It seems obvious that the two models could be merged. So I tried that.
My conclusion is that this is a lot of work for little benefit. There is no significant reduction in code or complexity.
An important aspect is that the
AttributeSet model contains more than just the fields:
Merging all that into
Subject would not really improve anything. So in the spirit of composition I would not merge this for now.