libnss-systemd 232-21ubuntu2 (amd64 binary) in ubuntu zesty

 nss-systemd is a plug-in module for the GNU Name Service Switch (NSS)
 functionality of the GNU C Library (glibc), providing UNIX user and group name
 resolution for dynamic users and groups allocated through the DynamicUser=
 option in systemd unit files. See systemd.exec(5) for details on this
 option.
 .
 Installing this package automatically adds the module to /etc/nsswitch.conf.