public function validateCustomer($nb_customer)
    {
        $nb_customer_id = nb_getMixedValue($nb_customer, NABU_CUSTOMER_FIELD_ID);
        return ($this instanceof CNabuDataObject) &&
               (is_numeric($nb_customer_id) || nb_isValidGUID($nb_customer_id)) &&
               $this->isValueEqualThan(NABU_CUSTOMER_FIELD_ID, $nb_customer_id)
        ;
    }