/usr/share/php/HTMLPurifier/AttrTransform/ is in php-htmlpurifier 4.6.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/HTMLPurifier/AttrTransform/Background.php
/usr/share/php/HTMLPurifier/AttrTransform/BdoDir.php
/usr/share/php/HTMLPurifier/AttrTransform/BgColor.php
/usr/share/php/HTMLPurifier/AttrTransform/BoolToCSS.php
/usr/share/php/HTMLPurifier/AttrTransform/Border.php
/usr/share/php/HTMLPurifier/AttrTransform/EnumToCSS.php
/usr/share/php/HTMLPurifier/AttrTransform/ImgRequired.php
/usr/share/php/HTMLPurifier/AttrTransform/ImgSpace.php
/usr/share/php/HTMLPurifier/AttrTransform/Input.php
/usr/share/php/HTMLPurifier/AttrTransform/Lang.php
/usr/share/php/HTMLPurifier/AttrTransform/Length.php
/usr/share/php/HTMLPurifier/AttrTransform/Name.php
/usr/share/php/HTMLPurifier/AttrTransform/NameSync.php
/usr/share/php/HTMLPurifier/AttrTransform/Nofollow.php
/usr/share/php/HTMLPurifier/AttrTransform/SafeEmbed.php
/usr/share/php/HTMLPurifier/AttrTransform/SafeObject.php
/usr/share/php/HTMLPurifier/AttrTransform/SafeParam.php
/usr/share/php/HTMLPurifier/AttrTransform/ScriptRequired.php
/usr/share/php/HTMLPurifier/AttrTransform/TargetBlank.php
/usr/share/php/HTMLPurifier/AttrTransform/Textarea.php