17 files declare their use of CacheableNormalization in Drupal 9

DataNormalizer.php in core/modules/jsonapi/src/Normalizer/DataNormalizer.php

EntityReferenceFieldNormalizer.php in core/modules/jsonapi/src/Normalizer/EntityReferenceFieldNormalizer.php

FieldItemNormalizer.php in core/modules/jsonapi/src/Normalizer/FieldItemNormalizer.php

FieldItemNormalizerTest.php in core/modules/jsonapi/tests/src/Kernel/Normalizer/FieldItemNormalizerTest.php

FieldNormalizer.php in core/modules/jsonapi/src/Normalizer/FieldNormalizer.php

JsonApiDocumentTopLevelNormalizer.php in core/modules/jsonapi/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php

LinkCollectionNormalizer.php in core/modules/jsonapi/src/Normalizer/LinkCollectionNormalizer.php

LinkCollectionNormalizerTest.php in core/modules/jsonapi/tests/src/Kernel/Normalizer/LinkCollectionNormalizerTest.php

NodeTest.php in core/modules/jsonapi/tests/src/Functional/NodeTest.php

NormalizerBase.php in core/modules/jsonapi/src/Normalizer/NormalizerBase.php

RelationshipNormalizer.php in core/modules/jsonapi/src/Normalizer/RelationshipNormalizer.php

RelationshipNormalizerTest.php in core/modules/jsonapi/tests/src/Kernel/Normalizer/RelationshipNormalizerTest.php

ResourceIdentifierNormalizer.php in core/modules/jsonapi/src/Normalizer/ResourceIdentifierNormalizer.php

ResourceObjectNormalizer.php in core/modules/jsonapi/src/Normalizer/ResourceObjectNormalizer.php

ResourceObjectNormalizerCacherTest.php in core/modules/jsonapi/tests/src/Kernel/EventSubscriber/ResourceObjectNormalizerCacherTest.php

ResourceResponseSubscriber.php in core/modules/jsonapi/src/EventSubscriber/ResourceResponseSubscriber.php

SerializerTest.php in core/modules/jsonapi/tests/src/Kernel/Serializer/SerializerTest.php