/usr/share/gtk-doc/html/librdf/librdf.devhelp2 is in librdf0-dev 1.0.17-1.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/gtk-doc/html/librdf/redland.devhelp2
/usr/share/gtk-doc/html/librdf/redland.devhelp2