12 files declare their use of PrimitiveInterface

AllowedValuesConstraintValidator.php in core/lib/Drupal/Core/Validation/Plugin/Validation/Constraint/AllowedValuesConstraintValidator.php
BinaryInterface.php in core/lib/Drupal/Core/TypedData/Type/BinaryInterface.php
BooleanInterface.php in core/lib/Drupal/Core/TypedData/Type/BooleanInterface.php
DecimalInterface.php in core/lib/Drupal/Core/TypedData/Type/DecimalInterface.php
FloatInterface.php in core/lib/Drupal/Core/TypedData/Type/FloatInterface.php
IntegerInterface.php in core/lib/Drupal/Core/TypedData/Type/IntegerInterface.php
PrimitiveDataNormalizer.php in core/modules/serialization/src/Normalizer/PrimitiveDataNormalizer.php
PrimitiveTypeConstraintValidatorTest.php in core/tests/Drupal/Tests/Core/Validation/Plugin/Validation/Constraint/PrimitiveTypeConstraintValidatorTest.php
SchemaCheckTrait.php in core/lib/Drupal/Core/Config/Schema/SchemaCheckTrait.php
StorableConfigBase.php in core/lib/Drupal/Core/Config/StorableConfigBase.php
StringInterface.php in core/lib/Drupal/Core/TypedData/Type/StringInterface.php
UriInterface.php in core/lib/Drupal/Core/TypedData/Type/UriInterface.php

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