'Build and return a SecurityGroupList.
:param security_groups: list of requested security group names or uuids
:type security_groups: list
:returns: nova.objects.security_group.SecurityGroupList'

def populate_security_groups(self, security_groups):

    if (not security_groups):
        return security_group_obj.SecurityGroupList()
    return security_group_obj.make_secgroup_list(security_groups)
