Modify ApprovalsMgmt in NAV 2016

Hi to all,

I have a task, to do some modification in Sales Approvals Management. I do that in CU:439 Approvals Management in functon FindApproverSales in NAV 2013.

But now in NAV 2016 I can't find a CU:439. On page Sales Order on Page Action "Send Approval Request" I see the code:

IF ApprovalsMgmt.CheckSalesApprovalsWorkflowEnabled(Rec) THEN
ApprovalsMgmt.OnSendSalesDocForApproval(Rec);

where ApprovalsMgmt is CU:1535 in NAV 2016 and OnSendSalesDocForApproval is Event with out code.
[IntegrationEvent] OnSendSalesDocForApproval(VAR SalesHeader : Record "Sales Header")

Can please somebody tell me how to find the code that execute calling the ApprovalsMgmt.OnSendSalesDocForApproval(Rec);

Thanks a lot,
Best Regards,