7 files declare their use of CacheContextInterface in Drupal 10

BookNavigationCacheContext.php in core/modules/book/src/Cache/BookNavigationCacheContext.php

CacheContextsManagerTest.php in core/tests/Drupal/Tests/Core/Cache/Context/CacheContextsManagerTest.php

Contains \Drupal\Tests\Core\Cache\Context\CacheContextsManagerTest.

ConfigOverrideIntegrationTestCacheContext.php in core/modules/config/tests/config_override_integration_test/src/Cache/ConfigOverrideIntegrationTestCacheContext.php

EntityTestViewGrantsCacheContext.php in core/modules/system/tests/modules/entity_test/src/Cache/EntityTestViewGrantsCacheContext.php

PirateDayCacheContext.php in core/modules/config/tests/config_override_test/src/Cache/PirateDayCacheContext.php

ViewsTestCacheContext.php in core/modules/views/tests/modules/views_test_data/src/Cache/ViewsTestCacheContext.php

WorkspaceCacheContext.php in core/modules/workspaces/src/WorkspaceCacheContext.php