/usr/share/php/sabre21/Sabre/DAV/Property/ is in php-sabre-dav-2.1 2.1.10-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/sabre21/Sabre/DAV/Property/GetLastModified.php
/usr/share/php/sabre21/Sabre/DAV/Property/Href.php
/usr/share/php/sabre21/Sabre/DAV/Property/HrefList.php
/usr/share/php/sabre21/Sabre/DAV/Property/IHref.php
/usr/share/php/sabre21/Sabre/DAV/Property/LockDiscovery.php
/usr/share/php/sabre21/Sabre/DAV/Property/ResourceType.php
/usr/share/php/sabre21/Sabre/DAV/Property/Response.php
/usr/share/php/sabre21/Sabre/DAV/Property/ResponseList.php
/usr/share/php/sabre21/Sabre/DAV/Property/SupportedLock.php
/usr/share/php/sabre21/Sabre/DAV/Property/SupportedMethodSet.php
/usr/share/php/sabre21/Sabre/DAV/Property/SupportedReportSet.php
/usr/share/php/sabre21/Sabre/DAV/PropertyStorage/Backend/
/usr/share/php/sabre21/Sabre/DAV/PropertyStorage/Backend/BackendInterface.php
/usr/share/php/sabre21/Sabre/DAV/PropertyStorage/Backend/PDO.php
/usr/share/php/sabre21/Sabre/DAV/PropertyStorage/Plugin.php