7 files declare their use of UseCacheBackendTrait in Drupal 8

DefaultPluginManager.php in core/lib/Drupal/Core/Plugin/DefaultPluginManager.php

EntityDisplayRepository.php in core/lib/Drupal/Core/Entity/EntityDisplayRepository.php

EntityFieldManager.php in core/lib/Drupal/Core/Entity/EntityFieldManager.php

EntityTypeBundleInfo.php in core/lib/Drupal/Core/Entity/EntityTypeBundleInfo.php

ProviderRepository.php in core/modules/media/src/OEmbed/ProviderRepository.php

ResourceFetcher.php in core/modules/media/src/OEmbed/ResourceFetcher.php

UrlResolver.php in core/modules/media/src/OEmbed/UrlResolver.php