in lib/gitlab/feature_flag_alert/monitor.rb [105:126]
def prepared_assignees(group_label)
return if group_label.nil?
_, group = group_definition(group_label)
return if group.nil?
prepared = group.values_at(
"backend_engineering_managers",
"frontend_engineering_managers",
"fullstack_managers",
"engineering_managers"
).flatten.compact.uniq
return if prepared.empty?
prepared.map { |username| "@#{username}" }.join(" ")
end