9 files declare their use of Activity in Open Social 8.4

ActivityDigestWorker.php in modules/custom/activity_send/modules/activity_send_email/src/Plugin/QueueWorker/ActivityDigestWorker.php

ActivityFactory.php in modules/custom/activity_creator/src/ActivityFactory.php

ActivityNotifications.php in modules/custom/activity_creator/src/ActivityNotifications.php

ActivitySendEmailWorker.php in modules/custom/activity_send/modules/activity_send_email/src/Plugin/QueueWorker/ActivitySendEmailWorker.php

activity_creator.module in modules/custom/activity_creator/activity_creator.module

Activity Creator module file.

EmailFrequencyBase.php in modules/custom/activity_send/modules/activity_send_email/src/EmailFrequencyBase.php

EmailFrequencyInterface.php in modules/custom/activity_send/modules/activity_send_email/src/EmailFrequencyInterface.php

Immediately.php in modules/custom/activity_send/modules/activity_send_email/src/Plugin/EmailFrequency/Immediately.php

None.php in modules/custom/activity_send/modules/activity_send_email/src/Plugin/EmailFrequency/None.php