Getting {"errors":{"gift_card":"Required parameter missing or invalid"}}

[jstolop]

I am posting to the giftcard api:

https://%data.storeUrl%/admin/api/2023-07/gift_cards.json"

using these headers:

httpRequest.addParam(type="header", name="Content-Type", value="application/json");
httpRequest.addParam(type="header", name="X-Shopify-Access-Token", value=accessToken);
httpRequest.addParam(type="header", name="api_version", value="2023-07");

with the following payload:

giftCardData = {
"gift_card": {
"note": "A gift card for you",
"initial_value": 50.00,
"code": "GIFT_CARD_CODE",
"template_suffix": "gift_cards.birthday.liquid"
}
};

However, I am getting this error

{"errors":{"gift_card":"Required parameter missing or invalid"}}

What am I doing wrong?