Without this, the user cannot configure only certain logging domains
without touching them all.
E.g.
# nmcli general logging level DEBUG domains PLATFORM
will disable all non-PLATFORM domains.
Well, the user can do:
# nmcli general logging level INFO domains PLATFORM:DEBUG
# nmcli general logging level DEBUG domains ALL:INFO,PLATFORM
but in this case all non-PLATFORM domains are reset explicitly.
Now the user can:
# nmcli general logging level KEEP domains PLATFORM:DEBUG
# nmcli general logging level DEBUG domains ALL:KEEP,PLATFORM
which will only change the platform domain.
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