6 files declare their use of CacheableResponseTrait in Drupal 9

CacheableResourceResponse.php in core/modules/jsonapi/src/CacheableResourceResponse.php

CacheableSecuredRedirectResponse.php in core/lib/Drupal/Core/Routing/CacheableSecuredRedirectResponse.php

CacheableTestResponse.php in core/modules/system/tests/modules/early_rendering_controller_test/src/CacheableTestResponse.php

HtmlResponse.php in core/lib/Drupal/Core/Render/HtmlResponse.php

ResourceResponse.php in core/modules/rest/src/ResourceResponse.php

SectionComponentBuildRenderArrayEvent.php in core/modules/layout_builder/src/Event/SectionComponentBuildRenderArrayEvent.php