9 classes are annotated with ActivityContext in Open Social 8

CommunityActivityContext in modules/custom/activity_basics/src/Plugin/ActivityContext/CommunityActivityContext.php

Provides a 'CommunityActivityContext' acitivy context.

ContentInMyGroupActivityContext in modules/custom/activity_basics/src/Plugin/ActivityContext/ContentInMyGroupActivityContext.php

Provides a 'ContentInMyGroupActivityContext' acitivy context.

FollowContentActivityContext in modules/social_features/social_follow_content/src/Plugin/ActivityContext/FollowContentActivityContext.php

Provides a 'FollowContentActivityContext' activity context plugin.

GroupActivityContext in modules/custom/activity_basics/src/Plugin/ActivityContext/GroupActivityContext.php

Provides a 'GroupActivityContext' activity context.

MentionActivityContext in modules/social_features/social_mentions/src/Plugin/ActivityContext/MentionActivityContext.php

Provides a 'MentionActivityContext' activity context.

OwnerActivityContext in modules/custom/activity_basics/src/Plugin/ActivityContext/OwnerActivityContext.php

Provides a 'OwnerActivityContext' activity context.

PrivateMessageActivityContext in modules/social_features/social_private_message/src/Plugin/ActivityContext/PrivateMessageActivityContext.php

Provides a 'PrivateMessageActivityContext' activity context.

ProfileActivityContext in modules/custom/activity_basics/src/Plugin/ActivityContext/ProfileActivityContext.php

Provides a 'ProfileActivityContext' activity context.

VoteActivityContext in modules/social_features/social_like/src/Plugin/ActivityContext/VoteActivityContext.php

Provides a 'VoteActivityContext' activity context.