Update an existing resource subscription's delivery schedule or recipients.

Supplied emails and slackChannelIDs replace their complete recipient lists; omission retains them. emails must remain nonempty, while [] clears Slack channels. Schedule fields use UTC. Delivery needs dayOfWeek for weekly schedules and both dayOfWeek and weekOfMonth (FIRST or LAST occurrence of that weekday) for monthly schedules. The API accepts schedules missing these fields, but they never match a delivery schedule.

PATCH cannot move a subscription to another resource or tenant.