[2.1-develop][Backport] Transport variable can not be altered in email_invoice_set_template_vars_before Event

[gwharton]

Fix missing commits from #10210 Transport variable can not be altered in email_invoice_set_template_vars_before Event

Description

Original commit in #10210 missed updates to the /app/code/Magento/Sales/Model/Order/Email/Sender/OrderSender.php file

Fixed Issues (if relevant)

1. Transport variable can not be altered in email_invoice_set_template_vars_before Event #10210

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[VladimirZaets]

Hi, @gwharton , I took your PR into processing, thank you for collaboration.

[VladimirZaets]

Hi, @gwharton, due to Magento backward-compatible guide we can't rename or remove event arguments or change their type.

Adding the new arguments is allowed. If it doesn't help, you can introduce new event argument with new name or type and deprecate the old argument by adding @deprecated annotation before dispatching the event

[gwharton]

This is what has been done. $transport = $transportObject->getData() therefore the original arguments have not changed type or name. We introduce a new argument $transportObject

[magento-engcom-team]

Hi @gwharton. Thank you for your contribution.
Changes from your Pull Request will be available with the upcoming 2.1.15 release.