OptionaleventPrefer resourceId over eventOccurredAt; it's harder to misuse.
If an event triggered your workflow and it doesn't have a unique ID, you may decide to use its occurrence timestamp. For example, if you have a daily CRON job, use the date it ran.
Use .toISOString().
The recipients in the chunk; maximum of MAXIMUM_RECIPIENTS_COUNT.
OptionalresourceIf a resource triggered your workflow, include its unique ID.
Note: workflowKey, recipients, and workplaceId (if it exists in the trigger body) are
included in the idempotency key automatically.
The workflow key.
The recipient chunk number.