8 files declare their use of AlterableInterface in Zircon Profile 8

database_test.module in core/modules/system/tests/modules/database_test/database_test.module

DefaultSelection.php in core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php

Contains \Drupal\Core\Entity\Plugin\EntityReferenceSelection\DefaultSelection.

GroupwiseMax.php in core/modules/views/src/Plugin/views/relationship/GroupwiseMax.php

Contains \Drupal\views\Plugin\views\relationship\GroupwiseMax.

node.module in core/modules/node/node.module

The core module that allows content to be submitted to the site.

QueryInterface.php in core/lib/Drupal/Core/Entity/Query/QueryInterface.php

Contains \Drupal\Core\Entity\Query\QueryInterface.

search_query_alter.module in core/modules/search/tests/modules/search_query_alter/search_query_alter.module

Test module that alters search queries.

system.module in core/modules/system/system.module

Configuration system that lets administrators modify the workings of the site.

views.module in core/modules/views/views.module

Primarily Drupal hooks and global API functions to manipulate views.