Fix AttributeError with third-party L3 service plugins
A recent patch fix for the Rocky branch from
20fd026116 have introduced an
AttributeError on Third Party Plugins that does not implement
This is just related to FWaaSv1 and only applicable to Rocky and below
This change fixes an issue where in the course of sending firewall
update notifications to the appropriate agents an AttributeError
is encountered due to unsafe assumption of the availability of L3
extensions on the l3_plugin.
This change puts protections in place to avoid this issue.
(cherry picked from commit