/usr/share/php/XML/RPC2/Backend/ is in php-xml-rpc2 1.1.2-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/XML/RPC2/Backend/Php/
/usr/share/php/XML/RPC2/Backend/Php/Client.php
/usr/share/php/XML/RPC2/Backend/Php/Request.php
/usr/share/php/XML/RPC2/Backend/Php/Response.php
/usr/share/php/XML/RPC2/Backend/Php/Server.php
/usr/share/php/XML/RPC2/Backend/Php/Value/
/usr/share/php/XML/RPC2/Backend/Php/Value.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Array.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Base64.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Boolean.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Datetime.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Double.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Integer.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Integer64.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Nil.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Scalar.php
/usr/share/php/XML/RPC2/Backend/Php/Value/String.php
/usr/share/php/XML/RPC2/Backend/Php/Value/Struct.php
/usr/share/php/XML/RPC2/Backend/Xmlrpcext/
/usr/share/php/XML/RPC2/Backend/Xmlrpcext/Client.php
/usr/share/php/XML/RPC2/Backend/Xmlrpcext/Server.php
/usr/share/php/XML/RPC2/Backend/Xmlrpcext/Value.php