/usr/share/php/sabre21/Sabre/ is in php-sabre-http-3 3.0.5-3.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/sabre21/Sabre/HTTP/
/usr/share/php/sabre21/Sabre/HTTP/Auth/
/usr/share/php/sabre21/Sabre/HTTP/Auth/AWS.php
/usr/share/php/sabre21/Sabre/HTTP/Auth/AbstractAuth.php
/usr/share/php/sabre21/Sabre/HTTP/Auth/Basic.php
/usr/share/php/sabre21/Sabre/HTTP/Auth/Digest.php
/usr/share/php/sabre21/Sabre/HTTP/Client.php
/usr/share/php/sabre21/Sabre/HTTP/ClientException.php
/usr/share/php/sabre21/Sabre/HTTP/ClientHttpException.php
/usr/share/php/sabre21/Sabre/HTTP/HttpException.php
/usr/share/php/sabre21/Sabre/HTTP/Message.php
/usr/share/php/sabre21/Sabre/HTTP/MessageDecoratorTrait.php
/usr/share/php/sabre21/Sabre/HTTP/MessageInterface.php
/usr/share/php/sabre21/Sabre/HTTP/Request.php
/usr/share/php/sabre21/Sabre/HTTP/RequestDecorator.php
/usr/share/php/sabre21/Sabre/HTTP/RequestInterface.php
/usr/share/php/sabre21/Sabre/HTTP/Response.php
/usr/share/php/sabre21/Sabre/HTTP/ResponseDecorator.php
/usr/share/php/sabre21/Sabre/HTTP/ResponseInterface.php
/usr/share/php/sabre21/Sabre/HTTP/Sapi.php
/usr/share/php/sabre21/Sabre/HTTP/URLUtil.php
/usr/share/php/sabre21/Sabre/HTTP/Util.php
/usr/share/php/sabre21/Sabre/HTTP/Version.php
/usr/share/php/sabre21/Sabre/HTTP/autoload.php