11 files declare their use of EntitySubqueue in Entityqueue 8

AddItemToSubqueue.php in src/Plugin/RulesAction/AddItemToSubqueue.php

ClearSubqueueItems.php in src/Plugin/RulesAction/ClearSubqueueItems.php

entityqueue.module in ./entityqueue.module

Allows users to collect entities in arbitrarily ordered lists.

EntityQueueCacheTagsTest.php in tests/src/Kernel/EntityQueueCacheTagsTest.php

EntityQueueListBuilder.php in src/EntityQueueListBuilder.php

entityqueue_smartqueue.module in modules/entityqueue_smartqueue/entityqueue_smartqueue.module

Provides automated subqueues for each entity of a given entity type.

RemoveItemFromSubqueue.php in src/Plugin/RulesAction/RemoveItemFromSubqueue.php

ReverseSubqueueItems.php in src/Plugin/RulesAction/ReverseSubqueueItems.php

ShuffleSubqueueItems.php in src/Plugin/RulesAction/ShuffleSubqueueItems.php

Simple.php in src/Plugin/EntityQueueHandler/Simple.php

SmartQueue.php in modules/entityqueue_smartqueue/src/Plugin/EntityQueueHandler/SmartQueue.php