To register Callback URL in the Google Server in order to get notifications from Google Calendar for any event creation, modification or...

To register Callback URL in the Google Server in order to get
notifications from Google Calendar for any event creation, modification
or...

I executed
POST
https://www.googleapis.com/calendar/v3/calendars/calendarId/events/watch
by Javascript SDK by the following rule but it returns 500 errors(internal
server error).
how can i get correct response?
gapi.client.load('calendar', 'v3', function() {
var request = gapi.client.calendar.events.watch({
'calendarId': "7987969-kjh-998",
'id': "772928214898",
'type': "web_hook",
'address': "https://123.com/notifications/"
});
request.execute(function(resp) {
alert(resp);
console.log(resp);
});
}); <script
src="https://apis.google.com/js/client.js?onload=handleClientLoad"></script>