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