After successful validation of the invoice, this scenario could be connected upstream of SAP Central Invoice Management (CIM) to complete the payment process afterwards.
To simulate the upstream you could download a PDF snapshot file (via the Download Snapshot button) of the validated invoice an transfer it to the dedicated file upload directory which could be accessed by SAP Central Invoice Management (CIM).
In the current source code the Accept and Reject buttons are only triggering notifications - in a productive scenario this behaviour has to be enhanced to trigger a real upstream scenario.
See also: SAP Ariba Central Invoice Management