Cannot set key of conference solution in manifest file - google-apps-script

Question

I cannot set "key" property in manifest file of GSuit application
"conferenceSolution": [{
"onCreateFunction": "createConference",
"id": "messanger",
"name": "Some messanger",
"key": {
"type": "addOn"
},
"logoUrl": "https://logos.com/some/logo123.png"
}]
but on push, I get error that:
GaxiosError: "appsscript.json" has errors: Invalid manifest: unknown fields: [addOns.calendar.conferenceSolution[0].key]
at Gaxios._request (C:\Users\iyano\AppData\Roaming\npm\node_modules\#google\clasp\node_modules\gaxios\build\src\gaxios.js:85:23)
at processTicksAndRejections (internal/process/task_queues.js:93:5)
at async OAuth2Client.requestAsync (C:\Users\iyano\AppData\Roaming\npm\node_modules\#google\clasp\node_modules\google-auth-library\build\src\auth\oauth2client.js:350:18)

Answer 1

Sample request of how to create an event with conference data in Apps Script:
function myFunction() {
var calendarId = "primary";
var resource = {
"summary": "event with conference data",
"end": {
"date": "2020-04-10"
},
"start": {
"date": "2020-04-10"
},
"conferenceData": {
"createRequest": {
"requestId": "123",
"conferenceSolutionKey": {
"type": "eventNamedHangout"
}
}
}
};
var event=Calendar.Events.insert(resource, calendarId,{"conferenceDataVersion":"1"})
Logger.log(event.id);
}
If it is for an Addon - I assume that type should be addOn instead of eventNamedHangout.