14 files declare their use of NormalizerInterface in Zircon Profile 8

ChainEntityResolver.php in core/modules/serialization/src/EntityResolver/ChainEntityResolver.php

Contains \Drupal\serialization\EntityResolver\ChainEntityResolver.

Dummy.php in vendor/symfony/serializer/Tests/Fixtures/Dummy.php

EntityResolverInterface.php in core/modules/serialization/src/EntityResolver/EntityResolverInterface.php

Contains \Drupal\serialization\EntityResolver\EntityResolverInterface.

GetSetMethodNormalizerTest.php in vendor/symfony/serializer/Tests/Normalizer/GetSetMethodNormalizerTest.php

NormalizableTraversableDummy.php in vendor/symfony/serializer/Tests/Fixtures/NormalizableTraversableDummy.php

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

Contains \Drupal\serialization\Normalizer\NormalizerBase.

ObjectNormalizerTest.php in vendor/symfony/serializer/Tests/Normalizer/ObjectNormalizerTest.php

ScalarDummy.php in vendor/symfony/serializer/Tests/Fixtures/ScalarDummy.php

SerializationTestNormalizer.php in core/modules/serialization/tests/serialization_test/src/SerializationTestNormalizer.php

Contains \Drupal\serialization_test\SerializationTestNormalizer.

Serializer.php in vendor/symfony/serializer/Serializer.php

TargetIdResolver.php in core/modules/serialization/src/EntityResolver/TargetIdResolver.php

Contains \Drupal\serialization\EntityResolver\TargetIdResolver.

TestNormalizer.php in vendor/symfony/serializer/Tests/Normalizer/TestNormalizer.php

UuidReferenceInterface.php in core/modules/serialization/src/EntityResolver/UuidReferenceInterface.php

Contains \Drupal\serialization\EntityResolver\UuidReferenceInterface.

UuidResolver.php in core/modules/serialization/src/EntityResolver/UuidResolver.php

Contains \Drupal\serialization\EntityResolver\UuidResolver.