Calendar Stream component supports kind of an incremental polling by setting considerLastUpdate=true. However, this is problematic as even current events might have been updated a long time ago (e.g. recurring events) and setting updatedMin request parameter to such a value causes HTTP 410 error with message: "The requested minimum modification time lies too far in the past."
A proper synchronization logic should be implemented instead. Documentation: https://developers.google.com/calendar/v3/sync
Note that `syncToken` is incompatible with `orderBy`, `query`, `dateMin`, `updatedMin` and some other parameters.