More Webhook API Changes

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

sample/notifications/GetWebhook.php

@@ -0,0 +1,26 @@
+<?php
+
+// # Get Webhook Sample
+//
+// This sample code demonstrate how you can get a webhook, as documented here at:
+// https://developer.paypal.com/webapps/developer/docs/api/#get-a-webhook
+// API used: GET /v1/notifications/webhooks/<Webhook-Id>
+
+// ## Get Webhook ID.
+// In samples we are using CreateWebhook.php sample to get the created instance of webhook.
+// However, in real case scenario, we could use just the ID from database or retrieved from the form.
+/** @var \PayPal\Api\Webhook $webhook */
+$webhook = require 'CreateWebhook.php';
+$webhookId = $webhook->getId();
+
+// ### Get Webhook
+try {
+    $output = \PayPal\Api\Webhook::get($webhookId, $apiContext);
+} catch (Exception $ex) {
+    ResultPrinter::printError("Get a Webhook", "Webhook", null, $webhookId, $ex);
+    exit(1);
+}
+
+ResultPrinter::printResult("Get a Webhook", "Webhook", $output->getId(), null, $output);
+
+return $output;