8 files declare their use of EntityContextDefinition

ContextDefinitionTest.php in core/tests/Drupal/KernelTests/Core/Plugin/ContextDefinitionTest.php
ContextHandlerTest.php in core/tests/Drupal/KernelTests/Core/Plugin/ContextHandlerTest.php
ContextPluginTest.php in core/tests/Drupal/KernelTests/Core/Plugin/ContextPluginTest.php
EntityBundle.php in core/lib/Drupal/Core/Entity/Plugin/Condition/Deriver/EntityBundle.php
EntityContextDefinitionIsSatisfiedTest.php in core/tests/Drupal/Tests/Core/Plugin/Context/EntityContextDefinitionIsSatisfiedTest.php
OptionalContextConditionTest.php in core/tests/Drupal/KernelTests/Core/Plugin/Condition/OptionalContextConditionTest.php
PluginTestBase.php in core/tests/Drupal/KernelTests/Core/Plugin/PluginTestBase.php
TermRouteContext.php in core/modules/taxonomy/src/ContextProvider/TermRouteContext.php

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