Need Payload for itemsV2 RESTAPI in Upsert Mode to create/update EFF

Summary:

Need Payload for itemsV2 RESTAPI in Upsert Mode to create/update EFF

Content (please ensure you mask any confidential information):

We need to use following RESTAPI in Upsert-Mode

https://<<servername>>/fscmRestApi/resources/11.13.18.05/itemsV2/
Upsert-Mode = true

Requirement:
If data exists for an attribute group, EFF Record it should be updated
If data does not exist for an attribute group, EFF Record it should be created

Please share an example payload for this requirement

I am using following payload and it returns 200 OK. However, it does not update or create an EFF record

{
"OrganizationCode": "00",
"ItemId": 123,
"OrganizationId": 456,
"ItemClass": "XYZ",
"PrimaryUOMValue": "EA",
"ItemStatusValue": "Active",