The transactionId property has been introduced into Create Event API.
https://docs.microsoft.com/en-us/graph/api/user-post-events?view=graph-rest-1.0&tabs=http#example-1-create-an-event-in-the-specified-time-zone-and-assign-the-event-an-optional-transactionid-value

That would be great if the similar function is introduced into Update Event API. Sometimes our application need to do unnecessary retries due to network issue or Microsoft Graph issue, and it generates unnecessary event update messages.