Removed ModelAccessValidator in favor of Forward Compatilibity Issues

- Model Access Validator causes unnecessary issues in existing integrations.
- Causes merchant to break integration if configured incorrectly.

tests/PayPal/Test/Api/WebhookEventTest.php

@@ -209,17 +209,6 @@ class WebhookEventTest extends \PHPUnit_Framework_TestCase
         WebhookEvent::validateAndGetReceivedEvent('something-invalid', $mockApiContext);
     }
 
-    /**
-     * @dataProvider mockProvider
-     * @param $mockApiContext ApiContext
-     * @expectedException \PHPUnit_Framework_Error_Notice
-     * @expectedExceptionMessage It seems that PayPal\Api\WebhookEvent:setValid is a new field added to the API response. If not, create an issue at https://github.com/paypal/PayPal-PHP-SDK/issues
-     */
-    public function testValidateWebhookValidJSONWithMissingObject($obj, $mockApiContext)
-    {
-            WebhookEvent::validateAndGetReceivedEvent('{"valid":"json"}', $mockApiContext);
-    }
-
     /**
      * @dataProvider mockProvider
      * @param $mockApiContext ApiContext