Extend Magento 2.3 support

[sethobey]

Context

Adobe has extended security support for Magento 2 version 2.3 thru Q3 2022. This branch also removes or refactors some PHP 7.4-specific code features to increase potential legacy support, even if specific Magento or PHP versions are no longer supported.

Description

• Removes typed properties (not supported in PHP 7.3)
• Removes arrow functions (not supported in PHP 7.3)
• Removes optional constructor parameters for Magento 2.3 compatibility
• Refactor for PHPUnit 6.5.14 backwards compatibility
• Fix bug in Plugin\Sales\Model\OrderRepository::class when calling Collection::setItems()

Performance

Allows for PHP 7.3 compatibility - No performance impact

Testing

Automated testing

• All unit tests pass

Manual testing

• Require module
• Enable module
• magento setup:upgrade
• magento setup:di:compile
• Web Auth / Activation
• Nexus Sync
• Smartcalcs (via checkout)
• Smartcalcs (via adminhtml)
• Transaction Sync (auto)
• Transaction Sync (manual)
• Transaction Backfill (adminhtml)
• Transaction Backfill (CLI)
• Address Validation (checkout)
• Address Validation (adminhtml)
• Backup Rates
• Debug mode
• SalesOrder UI Metadata

Versions

• [X] Magento 2.4
• [X] Magento 2.3
• [X] Magento Open Source (CE)
• [ ] Magento Commerce (EE)
• [ ] Magento B2B
• [ ] Magento Cloud
• [X] PHP 7.4
• [X] PHP 7.3