8 files declare their use of TypedDataInternalPropertiesHelper in Drupal 8

ComplexDataNormalizer.php in core/modules/serialization/src/Normalizer/ComplexDataNormalizer.php

ContentEntityNormalizer.php in core/modules/hal/src/Normalizer/ContentEntityNormalizer.php

ContentEntityNormalizer.php in core/modules/serialization/src/Normalizer/ContentEntityNormalizer.php

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

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

ResourceIdentifier.php in core/modules/jsonapi/src/JsonApiResource/ResourceIdentifier.php

ResourceObject.php in core/modules/jsonapi/src/JsonApiResource/ResourceObject.php

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