curl --request POST \
  --url https://api.example.com/api/v1/customer/import \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "items": [
    {
      "externalId": "<string>",
      "affiliateExternalId": "<string>",
      "registrationDate": "2023-11-07T05:31:56Z",
      "externalTrackerId": "<string>",
      "username": "<string>",
      "brandId": "<string>",
      "externalBrandId": "<string>",
      "country": "<string>",
      "revShareExcluded": true,
      "cpaExcluded": true,
      "category": "<string>",
      "label": "<string>",
      "customParameter": "<string>",
      "referringUrl": "<string>"
    }
  ]
}
'

{
  "numImported": 123,
  "numDuplicates": 123,
  "numFailed": 123,
  "firstFailureId": "<string>",
  "firstFailureMessage": "<string>"
}