'Overwrite L3Scheduler\'s method to filter by availability zone.'

def get_ha_routers_l3_agents_counts(self, plugin, context, filters=None):

    all_routers_agents = super(AZLeastRoutersScheduler, self).get_ha_routers_l3_agents_counts(plugin, context, filters)
    if (filters is None):
        return all_routers_agents
    routers_agents = []
    for (router, agents) in all_routers_agents:
        az_hints = self._get_az_hints(router)
        if (az_hints and (filters['availability_zone'] not in az_hints)):
            continue
        routers_agents.append((router, agents))
    return routers_agents
