curl --request POST \
  --url https://sdk-api.playcamp.io/v1/client/coupons/validate \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "couponCode": "<string>"
}
'

{
  "data": {
    "valid": true,
    "couponCode": "<string>",
    "reward": [
      {
        "itemName": {},
        "itemId": "<string>",
        "itemQuantity": 123,
        "itemImageUrl": "<string>"
      }
    ],
    "itemName": {},
    "errorCode": "<string>",
    "errorMessage": "<string>"
  }
}