11 files declare their use of TemplateCollectionInterface in Courier 8

ChannelFormController.php in src/Controller/ChannelFormController.php

CourierGlobalCollectionInvalidTemplateTest.php in tests/src/Kernel/CourierGlobalCollectionInvalidTemplateTest.php

CourierGlobalCollectionTest.php in tests/src/Kernel/CourierGlobalCollectionTest.php

CourierManager.php in src/Service/CourierManager.php

CourierManagerInterface.php in src/Service/CourierManagerInterface.php

Contains \Drupal\courier\Service\CourierManagerInterface.

courier_system.module in courier_system/courier_system.module

GlobalTemplateCollectionManager.php in src/Service/GlobalTemplateCollectionManager.php

GlobalTemplateCollectionManagerInterface.php in src/Service/GlobalTemplateCollectionManagerInterface.php

Settings.php in courier_system/src/Form/Settings.php

TemplateCollection.php in src/Entity/TemplateCollection.php

TemplateEditForm.php in src/Form/TemplateEditForm.php