Merges changes into an existing brand-custom event, identified by
name and origin. Only supplied fields are applied: omitted
metadata and omitted properties are preserved, and no property is
deleted. The type of an already explicitly-defined property cannot
change. Optional metadata fields must be omitted rather than sent as
null. The merged event is returned.

Scopes:
events.write

Rate Limiting:
This endpoint is rate limited to 400 requests per minute.