Recurring downtime for HostGroups

Is there a way to apply a recurring downtime to a Hostgroups? The documentation says hosts and services only, but has no mentioned of Hostgroups.

I’ve tried

apply ScheduledDowntime "weekly-maintenance" to HostGroups {
  author = "admin"
  comment = "Weekly Maintenance"
  ranges = {
    friday = "12:00-15:00"
  }
  assign where host.groups == "Linux_HostGroups"
}

However, this fails the `icinga2 daemon -C" checks.

No, Hostgroups are just to group hosts, but you can apply it to all hosts in a group.

apply ScheduledDowntime "weekly-maintenance" to Hosts {
  author = "admin"
  comment = "Weekly Maintenance"
  ranges = {
    friday = "12:00-15:00"
  }
  assign where "Linux_HostGroups" in host.groups
}

I changed it back to to Hosts and the assign to use in as host.groups is an array and not a string.