curl --request GET \
  --url https://{cluster}.voucherify.io/v1/referrals/{campaignId}/members/{memberId}/holders \
  --header 'Authorization: Bearer <token>' \
  --header 'X-App-Id: <api-key>' \
  --header 'X-App-Token: <api-key>'

{
  "object": "list",
  "data_ref": "data",
  "data": [
    {
      "id": "rh_0e7213a6bc407b8639",
      "created_at": "2024-03-15T09:08:50.529Z",
      "redeemable_id": "v_jFVcN1f5ofg707z2G3GYWtMyKJ4usss4",
      "redeemable_object": "voucher",
      "campaign_id": "camp_td1gcD4feTAjUKQYfg40kWhN",
      "campaign_type": "REFERRAL_PROGRAM",
      "voucher_type": "DISCOUNT_VOUCHER",
      "customer_id": "cust_XDwHXVBSZZAJgjpHvrgUHx3J",
      "holder_role": "REFERRER",
      "object": "redeemable_holder"
    },
    {
      "id": "rh_0e6d0b84960f447f52",
      "created_at": "2024-03-11T11:20:54.093Z",
      "redeemable_id": "v_jFVcN1f5ofg707z2G3GYWtMyKJ4usss4",
      "redeemable_object": "voucher",
      "campaign_id": "camp_td1gcD4feTAjUKQYfg40kWhN",
      "campaign_type": "REFERRAL_PROGRAM",
      "voucher_type": "DISCOUNT_VOUCHER",
      "customer_id": "cust_1B9wkAcSz5O1Y4Zn8JPfKQm6",
      "holder_role": "REFEREE",
      "object": "redeemable_holder"
    }
  ],
  "total": 2,
  "has_more": false
}