More Webhook API Changes

- Updated API Models with Fixes
- Updated Samples
- Additional Functional Tests

sample/notifications/SearchWebhookEvents.php

@@ -0,0 +1,31 @@
+<?php
+
+// # 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
+
+// ## Get Webhook Instance
+// ## PLEASE NOTE:
+// 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.
+/** @var \PayPal\Api\Webhook $webhook */
+$webhook = require __DIR__ . '/../bootstrap.php';
+
+$params = array(
+   // 'start_time'=>'2014-12-06T11:00:00Z',
+   // 'end_time'=>'2014-12-12T11:00:00Z'
+);
+
+// ### Search Webhook events
+try {
+    $output = \PayPal\Api\WebhookEvent::all($params, $apiContext);
+} catch (Exception $ex) {
+    ResultPrinter::printError("Search Webhook events", "WebhookEventList", null, null, $ex);
+    exit(1);
+}
+
+ResultPrinter::printResult("Search Webhook events", "WebhookEventList", null, $params, $output);
+
+return $output;