curl --request GET \
  --url https://api.useaira.com/v1/invoices/{invoiceId}/discounts \
  --header 'X-API-KEY: <api-key>'

{
  "items": [
    {
      "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
      "targetIdempotencyKey": "<string>",
      "description": "<string>",
      "amount": 123,
      "isActive": true
    }
  ]
}