How is \Magento\Sales\Model\Order\Payment\Transaction\Builder::transactionAdditionalInfo declared and used?

Context: How is \Magento\Sales\Model\Order\Payment::transactionAdditionalInfo declared and used?

Declaration

Usages

1. \Magento\Sales\Model\Order\Payment\Transaction\Builder::setAdditionalInformation()

2. \Magento\Sales\Model\Order\Payment\Transaction\Builder::addAdditionalInformation()

3. \Magento\Sales\Model\Order\Payment\Transaction\Builder::reset()

4. \Magento\Sales\Model\Order\Payment\Transaction\Builder::build()

https://github.com/magento/magento2/blob/ffea3cd/app/code/Magento/Sales/Model/Order/Payment/Transaction/Builder.php#L198-L203

Details: How is \Magento\Sales\Model\Order\Payment\Transaction\Builder::build() implemented and used?