title: Google Calendar event Created/Updated/Deleted Webhook?
body: <p>I am developing a SPA webapp through which I add events to my users google calendar They have given permission for. However this is my first time using Google calendar API, and was unclear about how to retrieve my users existing events , or if they add new events or delete them. IS there an option to set a webhook within google calendar thus when the user makes any changes to the calendar I can receive the change. My current approach was to make multiple get requests but that seems very inefficient. How can I keep my app calendar in sync with all user created events.</p>