How is \Magento\Sales\Model\Order\Payment::capture() implemented and used?

Implementation

https://github.com/magento/magento2/blob/ffea3cd/app/code/Magento/Sales/Model/Order/Payment.php#L435-L448

Usages

1. \Magento\Sales\Model\Order\Payment::processAction()

https://github.com/magento/magento2/blob/ffea3cd/app/code/Magento/Sales/Model/Order/Payment.php#L411-L431

2. \Magento\Sales\Model\Order\Invoice.::capture()

https://github.com/magento/magento2/blob/ffea3cd/app/code/Magento/Sales/Model/Order/Invoice.php#L334-L346

How is \Magento\Sales\Model\Order\Invoice.::capture() implemented and used?