private static function initProvider($credentials = [])
    {
        return new Unsplash([
            'clientId' => isset($credentials['applicationId']) ? $credentials['applicationId'] : null,
            'clientSecret' => isset($credentials['secret']) ? $credentials['secret'] : null,
            'redirectUri' => isset($credentials['callbackUrl']) ? $credentials['callbackUrl'] : null
        ]);
    }