xml.title   "#{@group.name} activity"
xml.link    href: group_url(@group, rss_url_options), rel: "self", type: "application/atom+xml"
xml.link    href: group_url(@group), rel: "alternate", type: "text/html"
xml.id      group_url(@group)
xml.updated @events[0].updated_at.xmlschema if @events[0]

xml << render(@events) if @events.any?