curl --request POST \
  --url https://idaas.yourflexpay.com/api/v1/subjects \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "externalId": "<string>",
  "displayName": "<string>",
  "email": "<string>",
  "metadata": {},
  "imageUrl": "<string>"
}
'

{
  "success": true,
  "message": "<string>",
  "errorCode": "<string>",
  "data": {
    "id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "applicationId": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "applicationName": "<string>",
    "externalId": "<string>",
    "displayName": "<string>",
    "email": "<string>",
    "imageUrl": "<string>",
    "metadata": {},
    "createdAt": "2023-11-07T05:31:56Z"
  },
  "errors": [
    "<string>"
  ],
  "timestamp": "2023-11-07T05:31:56Z"
}