Get an invoice by its Id

{
  "success": true,
  "invoice": {
    "id": 0,
    "api_app": {
      "id": 0,
      "user_id": 0,
      "name": "string"
    },
    "amount": 0,
    "expiry": "2019-08-24T14:15:22Z",
    "status": "string",
    "items": [
      {
        "name": "string",
        "unit_amount": 0,
        "quantity": 0,
        "description": "string"
      }
    ],
    "breakdown": {
      "items_total": 0,
      "tax": 0,
      "shipping": 0
    },
    "requested_information": ["shipping_address"],
    "metadata": {},
    "payer": {}
  }
}