Tested 1.1ubuntu1.18.04.7~16.04.1. Candidates are adjusted:

root@x-uu-ref:~# dpkg -l unattended-upgrades | cat
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                Version                    Architecture Description
+++-===================-==========================-============-===========================================
ii  unattended-upgrades 1.1ubuntu1.18.04.7~16.04.1 all          automatic installation of security upgrades
root@x-uu-ref:~# grep invoke /var/lib/dpkg/info/unattended-upgrades.prerm
root@x-uu-ref:~# unattended-upgrade --dry-run --verbose --debug
Initial blacklisted packages: 
Initial whitelisted packages: 
Starting unattended upgrades script
Allowed origins are: o=Ubuntu,a=xenial, o=Ubuntu,a=xenial-security, o=UbuntuESM,a=xenial
Using (^linux-image|^linux-headers|^linux-image-extra|^linux-modules|^linux-modules-extra|^linux-signed-image|^kfreebsd-image|^kfreebsd-headers|^gnumach-image|^.*-modules|^.*-kernel|^linux-backports-modules-.*|^linux-modules-.*|^linux-tools|^linux-cloud-tools) regexp to find kernel packages
Using (^linux-image.*4.19.0-12-generic|^linux-headers.*4.19.0-12-generic|^linux-image-extra.*4.19.0-12-generic|^linux-modules.*4.19.0-12-generic|^linux-modules-extra.*4.19.0-12-generic|^linux-signed-image.*4.19.0-12-generic|^kfreebsd-image.*4.19.0-12-generic|^kfreebsd-headers.*4.19.0-12-generic|^gnumach-image.*4.19.0-12-generic|4.19.0-12-generic.*-modules|4.19.0-12-generic.*-kernel|^linux-backports-modules-.*.*4.19.0-12-generic|^linux-modules-.*.*4.19.0-12-generic|^linux-tools.*4.19.0-12-generic|^linux-cloud-tools.*4.19.0-12-generic) regexp to find running kernel packages
Checking: cloud-init ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: cloud-init=0.7.7~bzr1212-0ubuntu1
Checking: kmod ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: kmod=22-1ubuntu5
Checking: libc-bin ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: libc-bin=2.23-0ubuntu10
Checking: libc6 ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: libc6=2.23-0ubuntu10
Checking: libkmod2 ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: libkmod2=22-1ubuntu5
Checking: locales ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: locales=2.23-0ubuntu10
Checking: multiarch-support ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: multiarch-support=2.23-0ubuntu10
Checking: python-apt-common ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: python-apt-common=1.1.0~beta1build1
Checking: snapd ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: snapd=2.0.2
Checking: ubuntu-core-launcher ([<Origin component:'main' archive:'xenial-proposed' origin:'Ubuntu' label:'Ubuntu' site:'archive.ubuntu.com' isTrusted:True>])
adjusting candidate version: ubuntu-core-launcher=1.0.27.1
pkgs that look like they should be upgraded: 
Fetched 0 B in 0s (0 B/s)                                                                                         
fetch.run() result: 0
blacklist: []
whitelist: []
No packages found that can be upgraded unattended and no pending auto-removals
root@x-uu-ref:~#