Create a product

A unique string to ensure the request is processed only once. Must be unique per request. Valid for 24 hours. Successful (2xx) responses are stored and replayed for the key. On POST /v1/payments, a 502 PROVIDER_TEMPORARILY_UNAVAILABLE for a boleto payment is stored and replayed too: to recover that payment, repeat the request once with the same externalId and a new key. A retry of an earlier card payment request now returns 400 CARD_PAYMENTS_NOT_AVAILABLE_VIA_API instead of the stored response (201 or 502): recover that payment with GET /v1/payments/txid/{txId}, or with a create request with the same externalId, mode: "hosted" and methods: ["CARD"], no card object or card fields, and a new key.