/usr/share/ipa/updates/73-winsync.update is in freeipa-server 4.7.0~pre1+git20180411-2ubuntu2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | # Add a inetUser objectclass to the passsync user
dn: uid=passsync,cn=sysaccounts,cn=etc,$SUFFIX
addifexist: objectClass: inetUser
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