Using the following against a schedule that is active does not work:
/uimapi/maintenance_mode/{domain}/{hub}/{robot}/add_computer_systems_to_active_window/{schedule_id}
Using the following against a schedule that is active does work
/uimapi/maintenance_mode/{domain}/{hub}/{robot}/add_computer_systems_to_schedule/{schedule_id}
Release : 20.4
Component: maintenance_mode
add_computer_systems_to_active_window is going to be decommissioned in a future release of UIMAPI. add_computer_systems_to_schedule should be used instead.