# Collect mattributes introduced in 'self' with `visibility >= min_visibility`.
	fun collect_intro_mattributes(filter: ModelFilter): Set[MAttribute] do
		var res = new HashSet[MAttribute]
		for mproperty in collect_intro_mproperties(filter) do
			if not filter.accept_mentity(mproperty) then continue
			if mproperty isa MAttribute then res.add(mproperty)
		end
		return res
	end