11 files declare their use of Mapping

ConfigActionManager.php in core/lib/Drupal/Core/Config/Action/ConfigActionManager.php
ConfigEntityAdapterTest.php in core/tests/Drupal/KernelTests/Core/Entity/ConfigEntityAdapterTest.php
ConfigEntityValidationTestBase.php in core/tests/Drupal/KernelTests/Core/Config/ConfigEntityValidationTestBase.php
ConfigMapperManagerTest.php in core/modules/config_translation/tests/src/Unit/ConfigMapperManagerTest.php
ConfigSchemaTest.php in core/tests/Drupal/KernelTests/Core/Config/ConfigSchemaTest.php
InvalidConfigException.php in core/lib/Drupal/Core/Recipe/InvalidConfigException.php
LangcodeRequiredIfTranslatableValuesConstraintValidator.php in core/lib/Drupal/Core/Config/Plugin/Validation/Constraint/LangcodeRequiredIfTranslatableValuesConstraintValidator.php
MappingTest.php in core/tests/Drupal/KernelTests/Config/Schema/MappingTest.php
StorableConfigBase.php in core/lib/Drupal/Core/Config/StorableConfigBase.php
ValidKeysConstraint.php in core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/ValidKeysConstraint.php
ValidKeysConstraintValidator.php in core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/ValidKeysConstraintValidator.php

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