How can externalId for ProductOrderItem passed by external system be mapped in request and response?
In general, does TMF Open API support any construct to map external identifier for any TMF resource in any API? If yes, how? We could see ExternalIdentifier resource is attached to some of the resources (like ProductOrder in TMF 622) and not to some others.
The ExternalIdentifier complex data type is indeed intended for this purpose. But it needs to be added explicitly to each relevant entity by the API design lead for that entity.
If you need such and it is missing, feel free to add as a private extension in your API model.
Maybe ExternalIdentifier could be added to Entity or even to Addressable?
This would be a far-reaching change; even though it's nominally backward compatible I'd be hesitant to make such a major adjustment without full discussion of the implications.