public function setCreationDatetime($creation_datetime) : CNabuDataObject
    {
        if ($creation_datetime === null) {
            throw new ENabuCoreException(
                    ENabuCoreException::ERROR_NULL_VALUE_NOT_ALLOWED_IN,
                    array("\$creation_datetime")
            );
        }
        $this->setValue('nb_user_creation_datetime', $creation_datetime);
        
        return $this;
    }