7 files declare their use of UpdateEvent in Automatic Updates 8.2

ComposerExecutableValidator.php in src/Validator/ComposerExecutableValidator.php

DiskSpaceValidator.php in src/Validator/DiskSpaceValidator.php

PendingUpdatesValidator.php in src/Validator/PendingUpdatesValidator.php

TestChecker1.php in tests/modules/automatic_updates_test/src/ReadinessChecker/TestChecker1.php

Updater.php in src/Updater.php

UpdateVersionValidator.php in src/Validator/UpdateVersionValidator.php

WritableFileSystemValidator.php in src/Validator/WritableFileSystemValidator.php