'Return True if port has as a security group and it\'s value
is either [] or not is_attr_set, otherwise return False'

def _check_update_deletes_security_groups(self, port):

    if ((ext_sg.SECURITYGROUPS in port['port']) and (not (validators.is_attr_set(port['port'][ext_sg.SECURITYGROUPS]) and (port['port'][ext_sg.SECURITYGROUPS] != [])))):
        return True
    return False
