Creating webhook is sample purposes only. In real scenario, you dont need to create a new webhook everytime you want to search for a webhook events. This is made in a sample just to make sure there is minimum of one webhook to listen to.
'start_time'=>'2014-12-06T11:00:00Z', 'end_time'=>'2014-12-12T11:00:00Z'
Search Webhook Events Sample
This sample code demonstrate how to use this call to search for all webhook events., as documented here at: https://developer.paypal.com/docs/api/#search-webhook-events API used: GET /v1/notifications/webhooks-events