fix errors in tests and stubs

Signed-off-by: mesilov <mesilov.maxim@gmail.com>

Author: mesilov

tests/Unit/Stubs/NullCore.php

@@ -4,10 +4,15 @@
 
 namespace Bitrix24\SDK\Tests\Unit\Stubs;
 
+use Bitrix24\SDK\Core\ApiClient;
 use Bitrix24\SDK\Core\Commands\Command;
+use Bitrix24\SDK\Core\Contracts\ApiClientInterface;
 use Bitrix24\SDK\Core\Contracts\CoreInterface;
+use Bitrix24\SDK\Core\Credentials\Credentials;
+use Bitrix24\SDK\Core\Credentials\WebhookUrl;
 use Bitrix24\SDK\Core\Response\Response;
 use Psr\Log\NullLogger;
+use Symfony\Component\HttpClient\MockHttpClient;
 use Symfony\Component\HttpClient\Response\MockResponse;
 
 /**
@@ -28,4 +33,9 @@ public function call(string $apiMethod, array $parameters = []): Response
     {
         return new Response(new MockResponse(''), new Command('', []), new NullLogger());
     }
+
+    public function getApiClient(): ApiClientInterface
+    {
+        return new ApiClient(Credentials::createForWebHook(new WebhookUrl('')), new MockHttpClient(), new NullLogger());
+    }
 }