13 files declare their use of ComplexDataInterface in Drupal 10

AllowedValuesConstraintValidator.php in core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/AllowedValuesConstraintValidator.php

ArrayElement.php in core/lib/Drupal/Core/Config/Schema/ArrayElement.php

ComplexDataConstraintValidator.php in core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/ComplexDataConstraintValidator.php

ComplexDataNormalizerTest.php in core/modules/serialization/tests/src/Unit/Normalizer/ComplexDataNormalizerTest.php

Contains \Drupal\Tests\serialization\Unit\Normalizer\ComplexDataNormalizerTest.

ContentEntityNormalizerTest.php in core/modules/serialization/tests/src/Unit/Normalizer/ContentEntityNormalizerTest.php

EntityAdapter.php in core/lib/Drupal/Core/Entity/Plugin/DataType/EntityAdapter.php

EntityFieldTest.php in core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php

FieldItemInterface.php in core/lib/Drupal/Core/Field/FieldItemInterface.php

IsNullConstraintValidator.php in core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/IsNullConstraintValidator.php

ItemList.php in core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php

Map.php in core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php

NotNullConstraintValidator.php in core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/NotNullConstraintValidator.php

TypedConfigTest.php in core/tests/Drupal/KernelTests/Config/TypedConfigTest.php