19 files declare their use of ForwardCompatibilityTrait

ArgumentsResolverTest.php in core/tests/Drupal/Tests/Component/Utility/ArgumentsResolverTest.php
ContextTest.php in core/tests/Drupal/Tests/Component/Plugin/Context/ContextTest.php
DateTimePlusTest.php in core/tests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php
DefaultFactoryTest.php in core/tests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php
DocParserTest.php in core/tests/Drupal/Tests/Component/Annotation/Doctrine/DocParserTest.php
DrupalTestCaseTrait.php in core/tests/Drupal/Tests/DrupalTestCaseTrait.php
EmailValidatorTest.php in core/tests/Drupal/Tests/Component/Utility/EmailValidatorTest.php
FileCacheFactoryTest.php in core/tests/Drupal/Tests/Component/FileCache/FileCacheFactoryTest.php
FrontMatterTest.php in core/tests/Drupal/Tests/Component/FrontMatter/FrontMatterTest.php
ImageTest.php in core/tests/Drupal/Tests/Component/Utility/ImageTest.php
NestedArrayTest.php in core/tests/Drupal/Tests/Component/Utility/NestedArrayTest.php
PluginManagerBaseTest.php in core/tests/Drupal/Tests/Component/Plugin/PluginManagerBaseTest.php
PoStreamReaderTest.php in core/tests/Drupal/Tests/Component/Gettext/PoStreamReaderTest.php
PoStreamWriterTest.php in core/tests/Drupal/Tests/Component/Gettext/PoStreamWriterTest.php
ScaffoldTest.php in core/tests/Drupal/Tests/Composer/Plugin/Scaffold/Functional/ScaffoldTest.php
SemVerTest.php in core/tests/Drupal/Tests/Composer/Plugin/Unpack/SemVerTest.php
YamlDirectoryDiscoveryTest.php in core/tests/Drupal/Tests/Component/Discovery/YamlDirectoryDiscoveryTest.php
YamlDiscoveryTest.php in core/tests/Drupal/Tests/Component/Discovery/YamlDiscoveryTest.php
YamlTest.php in core/tests/Drupal/Tests/Component/Serialization/YamlTest.php

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