With the following configuration in globals.yml:
enable_ceilometer="no"
enable_designate="no"
enable_searchlight="yes"
neutron.conf is generated like following:
[oslo_messaging_notifications]
driver = messagingv2
topics =
=> topics value is missing.
This patch fix it.
Closes-Bug: #1671940
Change-Id: I28ab60c61882caaba823bab84f30f77e270f29b4