Issue #2188661 by sun, Berdir: Extension System, Part II: ExtensionDiscovery.

core/includes/bootstrap.inc

core/includes/common.inc

core/includes/install.core.inc

core/includes/install.inc

core/includes/module.inc

core/includes/theme.inc

core/lib/Drupal/Core/Config/InstallStorage.php

core/lib/Drupal/Core/DrupalKernel.php

.../Extension/Discovery/RecursiveExtensionFilterIterator.php

core/lib/Drupal/Core/Extension/Extension.php

core/lib/Drupal/Core/Extension/ExtensionDiscovery.php

core/lib/Drupal/Core/Extension/InfoParser.php

core/lib/Drupal/Core/Extension/ModuleHandler.php

core/lib/Drupal/Core/Extension/ModuleHandlerInterface.php

core/lib/Drupal/Core/Extension/ThemeHandler.php

core/lib/Drupal/Core/Extension/ThemeHandlerInterface.php

core/lib/Drupal/Core/Extension/UpdateModuleHandler.php

core/lib/Drupal/Core/SystemListing.php

core/lib/Drupal/Core/SystemListingInfo.php

core/lib/Drupal/Core/Utility/ProjectInfo.php