8 files declare their use of YamlDiscovery in Zircon Profile 8

BreakpointManager.php in core/modules/breakpoint/src/BreakpointManager.php

Contains \Drupal\breakpoint\BreakpointManager.

ConfigMapperManager.php in core/modules/config_translation/src/ConfigMapperManager.php

Contains \Drupal\config_translation\ConfigMapperManager.

ContextualLinkManager.php in core/lib/Drupal/Core/Menu/ContextualLinkManager.php

Contains \Drupal\Core\Menu\ContextualLinkManager.

LocalActionManager.php in core/lib/Drupal/Core/Menu/LocalActionManager.php

Contains \Drupal\Core\Menu\LocalActionManager.

LocalTaskIntegrationTestBase.php in core/tests/Drupal/Tests/Core/Menu/LocalTaskIntegrationTestBase.php

Contains \Drupal\Tests\Core\Menu\LocalTaskIntegrationTestBase.

LocalTaskManager.php in core/lib/Drupal/Core/Menu/LocalTaskManager.php

Contains \Drupal\Core\Menu\LocalTaskManager.

MenuLinkManager.php in core/lib/Drupal/Core/Menu/MenuLinkManager.php

Contains \Drupal\Core\Menu\MenuLinkManager.

YamlDiscoveryTest.php in core/tests/Drupal/Tests/Core/Plugin/Discovery/YamlDiscoveryTest.php

Contains \Drupal\Tests\Core\Plugin\Discovery\YamlDiscoveryTest.