Change record status: 
Project: 
Introduced in branch: 
9.4.x
Introduced in version: 
9.4.0
Description: 

A method getSiteMaintenanceMessage has been added to Drupal\Core\Site\MaintenanceModeInterface:

  /**
   * Gets the site maintenance message.
   *
   * @return \Drupal\Component\Render\MarkupInterface
   *   The formatted site maintenance message.
   */
  public function getSiteMaintenanceMessage();

In addition, Calling Drupal\Core\Site\MaintenanceMode::__construct() without the $config_factory argument is deprecated in drupal:9.4.0 and the $config_factory argument will be required in drupal:10.0.0.

Impacts: 
Module developers