Returns the contact that a tracking-log entry belongs to. eventId must be the id of a tracking log entry, as returned by GET /contacts/{id}/trackingLogs or GET /trackingLogs. It is not a contact id and not an event-tracking event name. Passing a contact id returns 404 (No Result found for TrackingLog) when no entry has that id, or the contact of an unrelated entry when one does, so a 200 does not mean the id spaces are interchangeable. To fetch a contact by contact id, use GET /contacts/{id} (get-contact) instead. To list the tracking events of a known contact, use GET /contacts/{id}/trackingLogs.