PaymentAdditionalInfoInterface
Magento\Payment\Api\Data\PaymentAdditionalInfoInterface
What it does
This interface defines a contract for storing additional payment information as key-value pairs in Magento 2.
Developers use it when they need to pass extra payment details (like transaction IDs, payment gateway responses, or custom data) that don't fit into standard payment fields.
It's particularly useful for payment gateway integrations that require storing supplementary information alongside the main payment data.