title: Google Calendar API don't return shared calendars
body: <p>Initial situation:</p>
  
  <ul>
  <li>In one of our services, we use a service account to call Google Calendar API.</li>
  <li>User can share their calendars with this technical account via its technical emailaddress
  (@.iam.gserviceaccount.com).</li>
  <li>As calendars are shared, we can query them via API (CalendarList/List:   <a href="https://developers.google.com/calendar/v3/reference/calendarList/list" rel="noreferrer">https://developers.google.com/calendar/v3/reference/calendarList/list</a>)</li>
  <li>All this was working fine for several years without problem.</li>
  </ul>
  
  <p>Current issue:</p>
  
  <ul>
  <li>As we have discovered recently, newly shared calendars are not returned via the API call anymore. Calendars shared in the past are still returned (!)</li>
  <li>We are aware of pageTokens and handle them - this couldn't be a problem. In case of one (test) account only 8 calendars are shared currently and we cannot get more.</li>
  <li>There is no error/warning during the call on backend side</li>
  <li>There is no error/warning/quota problem on the Google Developer Console</li>
  </ul>
  
  <p>We haven't received any warning/alert from Google about Calendar API changes or limitations of our account(s). Also I haven't found any publicly known issue/outage about Google Calendar.</p>
  
  <p>What could be the problem? </p>
  
  <p>Should I report it to Google? If yes how exactly? All I could found was a "Google Cloud Platform Free Trial Troubleshooter", where (apart from a suggest to use stackoverflow ;]) all I can do with a "specific question and technical support" is to "start a chat", which leads to an internal Google site (moma). Is there anything else I could try?</p>
  
  <p>Any help would be much appreciated!</p>
  
  <p><strong>UPDATE:</strong> 
  There as indirect trace/hint in official documents that Google has changed this behaviour of (automatically) accepting shared Calendars - compare the "Share an existing calendar" section's current and 2019 august version:</p>
  
  <ul>
  <li><a href="https://support.google.com/calendar/answer/37082?hl=en" rel="noreferrer">https://support.google.com/calendar/answer/37082?hl=en</a></li>
  <li><a href="https://web.archive.org/web/20190904092735/https://support.google.com/calendar/answer/37082?hl=en" rel="noreferrer">https://web.archive.org/web/20190904092735/https://support.google.com/calendar/answer/37082?hl=en</a></li>
  </ul>
  
  <p><strong>UPDATE 2</strong>
  I have managed to report this issue to Google thanks to @DaImTo (google account required):
  <a href="https://issuetracker.google.com/issues/148804709" rel="noreferrer">https://issuetracker.google.com/issues/148804709</a></p>
  
  <p>The point is the following: </p>
  
  <ul>
  <li>"Due to a recent change of behaviour, any account has to explicitly "accept" a Calendar that has been shared with them."</li>
  <li>Status: Won't Fix (Intended behavior)</li>
  </ul>