ServiceAccout has empty calendarList after sharing a calendar has been shaired with it - rest

Question

On creating a new service account via Google Console, when then sharing a calendar with the service account, the calendar doesn't appear in the calendarList response for the authenticated service account.
This was working okay for some time but appears to have started failing more recently.
Oddly, if I delete the shared account entry on the calendar and then add it back in, it usually works. It doesn't appear to be a time delay as have waited hours initially and always zero results in the calendar list, until removing the shared account on the calendar and resharing.
The following are steps I've used to reproduce:
In Google Console web UI, create a new service account with 'Furnish a new private key' selected to download the JSON key.
In the Google Calendar web UI, go to calendar settings and 'Share this calendar', then share the calendar with the service account email, then save the changes.
In REST calls, authenticate with the JSON key with POST call to oauth2/v3/token
Send GET request for calendar/v3/users/me/calendarList
then optionally to show it working...
Delete the service account share from the calendar and save.
Add the service account email to the calendar share and save.
Repeat steps 2 and 3. This time it will probably work.
This is partially a manual process for our end users to create a service account and share calendars via Google web UI. Note I've been using additional calendars on my own Google account to share with the service account (this reflects our end user use case), rather than just the default calendar.
Client code is REST based. To provide an example I have shown the REST requests and responses below. There are simply two requests, one to authenticate and one to fetch the calendarList. These occur after the manual steps in the UI to create a service account and then share a calendar with that account.
---
Request:
POST https://www.googleapis.com/oauth2/v3/token HTTP/1.1
Accept: application/json, application/xml, text/json, text/x-json, text/javascript, text/xml
User-Agent: RestSharp/105.2.3.0
Content-Type: application/x-www-form-urlencoded
Host: www.googleapis.com
Content-Length: 758
Accept-Encoding: gzip, deflate
Connection: Keep-Alive
grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Ajwt-bearer&assertion=[ASSERTION_JWT_HERE]
Response:
HTTP/1.1 200 OK
Cache-Control: no-cache, no-store, max-age=0, must-revalidate
Pragma: no-cache
Expires: Mon, 01 Jan 1990 00:00:00 GMT
Date: Tue, 14 Mar 2017 20:17:18 GMT
Vary: Origin
Vary: X-Origin
Content-Type: application/json; charset=UTF-8
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
Server: GSE
Alt-Svc: quic=":443"; ma=2592000; v="36,35,34"
Content-Length: 197
{
"access_token": "ya29.ElkOBAzSOzE_J2VOGFeWnTAGXdtoadW2FbnGga99SrMeamL7j6KetKomvT4aoy4jsRCcXpK-N6sxRBLFUaj_kPWFin4m6xvg_CtaTtkG5tVc_IxS7IezJDf32g",
"token_type": "Bearer",
"expires_in": 3600
}
---
---
Request
GET https://www.googleapis.com/calendar/v3/users/me/calendarList?minAccessRole=reader HTTP/1.1
Authorization: Bearer ya29.ElkOBAzSOzE_J2VOGFeWnTAGXdtoadW2FbnGga99SrMeamL7j6KetKomvT4aoy4jsRCcXpK-N6sxRBLFUaj_kPWFin4m6xvg_CtaTtkG5tVc_IxS7IezJDf32g
Accept: application/json, application/xml, text/json, text/x-json, text/javascript, text/xml
User-Agent: RestSharp/105.2.3.0
Host: www.googleapis.com
Accept-Encoding: gzip, deflate
Response:
HTTP/1.1 200 OK
Expires: Tue, 14 Mar 2017 20:17:19 GMT
Date: Tue, 14 Mar 2017 20:17:19 GMT
Cache-Control: private, max-age=0, must-revalidate, no-transform
Vary: Origin
Vary: X-Origin
Content-Type: application/json; charset=UTF-8
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
Content-Length: 202
Server: GSE
Alt-Svc: quic=":443"; ma=2592000; v="36,35,34"
{
"kind": "calendar#calendarList",
"etag": "\"p328bl14pt3bd40g\"",
"nextSyncToken": "CJC6hJno1tICEj10ZXN0MS05MjhAY2FsZW5kYXItY29ubmVjdG9yLS0tb25lbGFuLmlhbS5nc2VydmljZWFjY291bnQuY29t",
"items": []
}
---
Note, I haven't provided the actual JWT for the ouath request, but the authentication is working fine. Also note the calendar is shared as either read or modify with the service account. I can also query the calendar itself and fetch events using the service account, but it is querying the list of calendars associated with the account that fails.
Had also raised this as an issue here but posting this here also in case I'm missing something, although as said all this was working fine until more recently, and our existing unchanged client software has started failing with newly created service accounts.

Answer 1

When you share a calendar with someone VIA the google calendar website the code on the website automatically adds the calendar to the users calendar.list. All the calendarlist is the list on the bottom left of the google calendar website. A user can have access to a calendar without it being in their calendarlist.
When sharing a calendar wish a service account this does not always happen. None of the service accounts I have shared my calendars with have ever had anything in their calendarlist. If you need it to be in the calendarlist then you should have the service account insert it. Using CalendarList: insert just grab the calendar id in question off of the website.