7 files declare their use of ContextProviderInterface

CurrentLanguageContext.php in core/lib/Drupal/Core/Language/ContextProvider/CurrentLanguageContext.php
CurrentUserContext.php in core/modules/user/src/ContextProvider/CurrentUserContext.php
FakeViewModeContext.php in core/modules/layout_builder/tests/modules/layout_builder_fieldblock_test/src/ContextProvider/FakeViewModeContext.php
IHaveRuntimeContexts.php in core/modules/layout_builder/tests/modules/layout_builder_test/src/ContextProvider/IHaveRuntimeContexts.php
MultipleStaticContext.php in core/modules/block/tests/modules/block_test/src/ContextProvider/MultipleStaticContext.php
NodeRouteContext.php in core/modules/node/src/ContextProvider/NodeRouteContext.php
TermRouteContext.php in core/modules/taxonomy/src/ContextProvider/TermRouteContext.php

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