11 files declare their use of VocabularyInterface in Drupal 9

forum.module in core/modules/forum/forum.module

Provides discussion forums.

ForumUninstallValidator.php in core/modules/forum/src/ForumUninstallValidator.php

MigrateTaxonomyVocabularyTest.php in core/modules/taxonomy/tests/src/Kernel/Migrate/d7/MigrateTaxonomyVocabularyTest.php

Overview.php in core/modules/forum/src/Form/Overview.php

OverviewTerms.php in core/modules/taxonomy/src/Form/OverviewTerms.php

TaxonomyController.php in core/modules/taxonomy/src/Controller/TaxonomyController.php

TaxonomyTestTrait.php in core/modules/taxonomy/tests/src/Traits/TaxonomyTestTrait.php

taxonomy_crud.module in core/modules/taxonomy/tests/modules/taxonomy_crud/taxonomy_crud.module

Provides hook implementations for testing purposes.

Vocabulary.php in core/modules/taxonomy/src/Entity/Vocabulary.php

VocabularyResponse.php in core/modules/taxonomy/tests/modules/vocabulary_serialization_test/src/VocabularyResponse.php

VocabularySerializationTestController.php in core/modules/taxonomy/tests/modules/vocabulary_serialization_test/src/VocabularySerializationTestController.php