curl --request POST \
  --url http://localhost:6900/v1/customers \
  --header 'Content-Type: application/json' \
  --data '
{
  "environment_id": "<string>",
  "user_id": "<string>",
  "provider_id": "<string>",
  "external_id": "<string>",
  "email": "jsmith@example.com",
  "name": "<string>",
  "phone": "<string>",
  "metadata": {}
}
'

{
  "id": "<string>"
}