msg.json

{
  "recipient": {
    "id": "1315593905118354"
  },
  "message": {
    "attachment": {
      "type": "template",
      "payload": {
        "template_type": "generic",
        "text": "",
        "buttons": null,
        "elements": [
          {
            "title": "Welcome",
            "subtitle": "This is an app to split bills and track debt records.",
            "default_action": {
              "type": "web_url",
              "url": "https://debtstracker-dev1.appspot.com/app/#fbm579129655604667",
              "messenger_extensions": true
            },
            "buttons": [
              {
                "type": "postback",
                "title": "📝  Debts",
                "payload": "fbm-debts"
              },
              {
                "type": "postback",
                "title": "📮  Bills",
                "payload": "fbm-bills"
              },
              {
                "type": "postback",
                "title": "⚙  Settings",
                "payload": "fbm-settings"
              }
            ]
          }
        ]
      }
    }
  },
  "notification_type": "NO_PUSH"
}