/etc/apparmor.d/usr.lib.dovecot.deliver is in apparmor-profiles 2.12-4ubuntu5.1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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#
#    Copyright (C) 2009 Dulmandakh Sukhbaatar <dulmandakh@gmail.com>
#    Copyright (C) 2009-2014 Canonical Ltd.
#    Copyright (C) 2011-2013 Christian Boltz
#
#    This program is free software; you can redistribute it and/or
#    modify it under the terms of version 2 of the GNU General Public
#    License published by the Free Software Foundation.
#
# ------------------------------------------------------------------
# vim: ft=apparmor
#include <tunables/global>
#include <tunables/dovecot>
/usr/lib/dovecot/deliver flags=(complain) {
  #include <abstractions/base>
  #include <abstractions/nameservice>
  #include <abstractions/dovecot-common>
  capability setuid,
  @{DOVECOT_MAILSTORE}/ rw,
  @{DOVECOT_MAILSTORE}/** rwkl,
  # http://www.postfix.org/SASL_README.html#server_dovecot
  /etc/dovecot/dovecot.conf r,
  /etc/dovecot/{auth,conf}.d/*.conf r,
  /etc/dovecot/dovecot-postfix.conf r, # ???
  @{HOME} r, # ???
  /usr/lib/dovecot/deliver mr,
  # Site-specific additions and overrides. See local/README for details.
  #include <local/usr.lib.dovecot.deliver>
}
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