collect_engine_routes

# File actionpack/lib/action_dispatch/routing/inspector.rb, line 130
      def collect_engine_routes(route)
        name = route.endpoint
        return unless route.engine?
        return if @engines[name]

        routes = route.rack_app.routes
        if routes.is_a?(ActionDispatch::Routing::RouteSet)
          @engines[name] = collect_routes(routes.routes)
        end
      end