# Collect all property definitions that are introductions in `self`
	fun collect_intro_mpropdefs(filter: nullable ModelFilter): Set[MPropDef] do
		var set = new HashSet[MPropDef]
		for mclassdef in mclassdefs do
			for mpropdef in mclassdef.mpropdefs do
				if not mpropdef.is_intro then continue
				if filter == null or filter.accept_mentity(mpropdef) then set.add(mpropdef)
			end
		end
		return set
	end