title: Google Calendar push notifications. Up to date flag
body: <p>I've subscribed on <a href="https://developers.google.com/google-apps/calendar/v3/push#making-watch-requests" rel="nofollow noreferrer">google calendar push notifications (PN)</a>. Base synchronization processes using PN. I need to know if all events already loaded in calendar scope or not.</p>
  
  <p>Is it possible to have a special marker in my request answer (request events for specified calendar based on subscribed channel information)?</p>
  
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  <p>If calendar has too much events, events will be loaded in few push notifications handling. I need marker for UI if calendar is synchronized completely. In my my usual logic I thought that calendar is already synchronized if first PN per calendar already handled. So I need notify my UI client with correct status (<code>calendar_is_synchronnized</code>, <code>calendar_is_not_synchronnized</code>) but I do not have any markers from google if the PN provides me load last events portion in specified calendar scope.</p>