Currently it is possible to put the master in maintenance mode, but that will not trigger a failover.
- it should not be possible to put the master in maintenance mode, but a switchover would have to be performed first, or
- if the master is put into maintenance mode, then that should trigger a failover.
The first alternative is better, as that does not lead to implicit actions. Essentially, in the case of a Master/Slave cluster it should only be possible to put a slave in maintenance mode.