Notice: Message is undefined in Transport

[niziou]

Please take a look at:

magento2-plugin/Model/Transport.php

Line 245 in 6c703d9

} elseif ( version_compare($this->_magVersion, "2.2.9", "<=") && $message instanceof \Zend_mail) {

While running integration tests I am getting:
PHP Notice: Undefined variable: message in /var/www/magento/gnp74/vendor/sendinblue/module-sendinblue/Model/Transport.php on line 245

When I changed the $message to $this->_message the notice went away but I am not sure if this was intended.