Make object enter or leave maintenance mode, immediately or on schedule

Without time fields, immediately changes object maintenance state according to the "maintenance" field. If "startTime" and/or "endTime" is provided, maintenance is scheduled instead by creating one-time scheduled tasks (visible in scheduled task list and cancellable via the scheduled tasks API):

• startTime + endTime - schedule maintenance window (enter at startTime, leave at endTime);
• startTime only - schedule maintenance entry, leave manually;
• endTime only - schedule maintenance exit; combined with "maintenance": true the object enters maintenance immediately and leaves at endTime. Scheduling requires the "schedule object maintenance" system access right.