PATCH <serviceroot>/api/data/v8.0/calendars(id of the record)
|Absence of both If-Match and If-None-Match header||Upsert
if record already exists, updates it else Creates it.
|If-Match: “*”||Update Only
Create does not happen because If-Match:”*” fails if the record does not exist
|If-None-Match : “*”||Create Only
Update does not happen because If-None-Match:”*” fails if the record already exists