curl --request GET \
  --url https://test.didxtech.com/consumer-onboarding/api/users/{username}/external-identifier \
  --header 'Authorization: Bearer <token>'

{
  "data": {
    "externalIdentifier": "PARTNER-ID-12345"
  },
  "links": {
    "self": "<string>",
    "first": "<string>",
    "last": "<string>",
    "prev": "<string>",
    "next": "<string>",
    "related": "<string>"
  },
  "meta": {},
  "errors": [
    {
      "detail": "<string>",
      "id": "<string>",
      "status": "<string>",
      "code": "<string>",
      "title": "<string>",
      "source": {
        "pointer": "<string>",
        "parameter": "<string>"
      },
      "meta": {}
    }
  ]
}