oEmbed source plugin expects a response object when determining the thumbnail file extension

As of #3231731: Use Content-Type header from oEmbed thumbnail GET request when determining the file extension, the protected method \Drupal\media\Plugin\media\Source\OEmbed::getThumbnailFileExtensionFromUrl() expects to be passed an instance of \Psr\Http\Message\ResponseInterface. In the base implementation, the response's headers may be used to determine the thumbnail's file type.

For backwards compatibility, the base class currently allows the $response parameter to be NULL; if it is, and the thumbnail's file extension is not in the thumbnail's URL, the method will return NULL. However, passing NULL for the $response parameter is deprecated, and it will be a required parameter in Drupal 10.

To prevent PHP warnings, subclasses of \Drupal\media\Plugin\media\Source\OEmbed which override the getThumbnailFileExtensionFromUrl() method should adjust their code accordingly:

Before

protected function getThumbnailFileExtensionFromUrl(string $thumbnail_url): ?string {
  // Do magic...
}

Now

use Psr\Http\Message\ResponseInterface;

protected function getThumbnailFileExtensionFromUrl(string $thumbnail_url, ResponseInterface $response = NULL): ?string {
  // Do magic...
}