7 files declare their use of CronPlugin in Ultimate Cron 8.2

CronJobForm.php in src/Form/CronJobForm.php

LauncherBase.php in src/Launcher/LauncherBase.php

LoggerBase.php in src/Logger/LoggerBase.php

SchedulerBase.php in src/Plugin/ultimate_cron/Scheduler/SchedulerBase.php

UltimateCronCommands.php in src/Commands/UltimateCronCommands.php

ultimate_cron.drush.inc in ./ultimate_cron.drush.inc

Drush commands for Ultimate Cron!

ultimate_cron.module in ./ultimate_cron.module

Ultimate Cron. Extend cron functionality in Drupal.