Module handler service. Type:

Requirement severity -- Error condition; abort installation. File core/modules/system/src/SystemManager

public SystemManager::getAdminBlock(MenuLinkInterface $instance)

public SystemManager::listRequirements()

A static cache of menu items. Type:

public SystemManager::checkRequirements()

Requirement severity -- Warning condition; proceed but flag warning. File core/modules/system/src/SystemManager

System Manager Service. Hierarchy class \Drupal\system\

Requirement severity -- Requirement successfully met. File core/modules/system/src/SystemManager.php

The request stack. Type: \Symfony\Component\HttpFoundation\RequestStack File