/usr/lib/x86_64-linux-gnu/libubuntu-app-launch.so.4 is in libubuntu-app-launch4 0.12+17.04.20170404.2-0ubuntu6.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libubuntu-app-launch.so.4.0.0