// check for allowed_warnings
        $headers = $this->client->transport->getLastConnection()->getLastRequestInfo()['response']['headers'];
        if (isset($headers['Warning'])) {
            $expectedHeaders = :expected;
            $contains = false;
            foreach ($expectedHeaders as $expected) {
                $contains = $contains || (false !== strpos($headers['Warning'][0], $expected));
            }
            $this->assertTrue($contains);
        }