No more upsert in v2?

[amunrarara]

Back in v1, the functions generated for models included upsert: https://docs.medusajs.com/v1/references/product/upsert

V2, however, doesn't contain upsert: https://docs.medusajs.com/resources/service-factory-reference

Why no upsert?

[amunrarara]

I'm also noticing that the return value for a non-existing object isn't stated in the documentation: https://docs.medusajs.com/resources/service-factory-reference/methods/retrieve