curl --request POST \
  --url https://api.portable.io/v2/sources \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "sourceSpec": "google_calendar"
}'

{
  "data": {
    "id": 80190,
    "displayName": "John Doe's Google Calendar",
    "sourceSpec": "google_calendar",
    "properties": [
      {
        "name": "email",
        "displayName": "Email",
        "type": "string",
        "required": true,
        "description": "Email of the calendar's user",
        "value": ""
      }
    ],
    "createdAt": "2023‐06‐12T20:03:00Z",
    "updatedAt": "2023-08-01T00:00:00Z"
  }
}