6 files declare their use of FileFieldCreationTrait

DrupalSelenium2DriverTest.php in core/tests/Drupal/FunctionalJavascriptTests/Tests/DrupalSelenium2DriverTest.php
FileFieldValidateTest.php in core/modules/file/tests/src/FunctionalJavascript/FileFieldValidateTest.php
FileFieldWidgetTest.php in core/modules/file/tests/src/FunctionalJavascript/FileFieldWidgetTest.php
InlineBlockPrivateFilesTest.php in core/modules/layout_builder/tests/src/FunctionalJavascript/InlineBlockPrivateFilesTest.php
MaximumFileSizeExceededUploadTest.php in core/modules/file/tests/src/FunctionalJavascript/MaximumFileSizeExceededUploadTest.php
QuickEditFileTest.php in core/modules/quickedit/tests/src/FunctionalJavascript/QuickEditFileTest.php

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