7 files declare their use of EntityOwnerInterface in Zircon Profile 8

CommentInterface.php in core/modules/comment/src/CommentInterface.php

Contains \Drupal\comment\CommentInterface.

CommentStatistics.php in core/modules/comment/src/CommentStatistics.php

Contains \Drupal\comment\CommentStatistics.

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

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

EntityReferenceAutocompleteWidget.php in core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/EntityReferenceAutocompleteWidget.php

Contains \Drupal\Core\Field\Plugin\Field\FieldWidget\EntityReferenceAutocompleteWidget.

EntityTest.php in core/modules/system/tests/modules/entity_test/src/Entity/EntityTest.php

Contains \Drupal\entity_test\Entity\EntityTest.

FileInterface.php in core/modules/file/src/FileInterface.php

Contains \Drupal\file\FileInterface.

NodeInterface.php in core/modules/node/src/NodeInterface.php

Contains \Drupal\node\NodeInterface.