Upsert your Products. This endpoint is combination of bulk_update and bulk_create. Product identifier is "product_external_id" (with addion of optional "product_identifier"). If an matching product exists in JOOR, it will be updated. If matching Product does not exists in JOOR, it will be created. Endpoint is async, so endpoint will return a job_id which can be used to check a status. Default limit of objects which can be sent within single request is 20.