/usr/share/php/Symfony/Component/Serializer/Normalizer/ is in php-symfony-serializer 3.4.6+dfsg-1.
This file is owned by root:root, with mode 0o755.
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/usr/share/php/Symfony/Component/Serializer/Normalizer/AbstractNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/AbstractObjectNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/ArrayDenormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/ContextAwareDenormalizerInterface.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/ContextAwareNormalizerInterface.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/CustomNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/DataUriNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/DateIntervalNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/DateTimeNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/DenormalizableInterface.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/DenormalizerAwareInterface.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/DenormalizerAwareTrait.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/DenormalizerInterface.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/GetSetMethodNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/JsonSerializableNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/NormalizableInterface.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/NormalizerAwareInterface.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/NormalizerAwareTrait.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/NormalizerInterface.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/ObjectNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/ObjectToPopulateTrait.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/PropertyNormalizer.php
/usr/share/php/Symfony/Component/Serializer/Normalizer/SerializerAwareNormalizer.php