* nmcli: fix vlan connection modification Fixes#42322 (#42415)
* ensure optional items are set to empty strings rather than not presented
fix syntax of vlan modification command
* extended tests for nmcli
(cherry picked from commit fb72a5424c)
* Changelog fragment for nmcli fix
This fix check if DNS4 is None or not before proceeding with
other operations. Also, added unit test for this change.
Signed-off-by: Fedor Sumkin <qosys.net@gmail.com>
Signed-off-by: Abhijeet Kasurde <akasurde@redhat.com>
