/usr/lib/libreoffice/sdk/idl is in libreoffice-dev 1:3.5.2-2ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libreoffice/sdk/../../../share/idl/libreoffice
/usr/lib/libreoffice/sdk/../../../share/idl/libreoffice