14 files declare their use of EntityContextDefinition in Drupal 8

ContextHandlerTest.php in core/tests/Drupal/KernelTests/Core/Plugin/ContextHandlerTest.php

ContextPluginTest.php in core/tests/Drupal/KernelTests/Core/Plugin/ContextPluginTest.php

DefaultsSectionStorageTest.php in core/modules/layout_builder/tests/src/Unit/DefaultsSectionStorageTest.php

DefaultsSectionStorageTest.php in core/modules/layout_builder/tests/src/Kernel/DefaultsSectionStorageTest.php

Entity.php in core/modules/views/src/Plugin/views/argument_validator/Entity.php

EntityContextDefinitionDeprecationTest.php in core/tests/Drupal/Tests/Core/Plugin/Context/EntityContextDefinitionDeprecationTest.php

EntityContextDefinitionIsSatisfiedTest.php in core/tests/Drupal/Tests/Core/Plugin/Context/EntityContextDefinitionIsSatisfiedTest.php

ExtraFieldBlockDeriver.php in core/modules/layout_builder/src/Plugin/Derivative/ExtraFieldBlockDeriver.php

FieldBlockDeriver.php in core/modules/layout_builder/src/Plugin/Derivative/FieldBlockDeriver.php

FieldBlockTest.php in core/modules/layout_builder/tests/src/Kernel/FieldBlockTest.php

MockBlockManager.php in core/modules/system/tests/modules/plugin_test/src/Plugin/MockBlockManager.php

NodeRouteContext.php in core/modules/node/src/ContextProvider/NodeRouteContext.php

OptionalContextConditionTest.php in core/tests/Drupal/KernelTests/Core/Plugin/Condition/OptionalContextConditionTest.php

PluginTestBase.php in core/tests/Drupal/KernelTests/Core/Plugin/PluginTestBase.php