BPM - How to get SubmitToAgent Method

Trying to validate some data before Ap Inv Post through Method Directive. To do this, identified that the following method is being called:

Erp.Proxy.Proc.APInvoicePostImpl
** SubmitToAgent**

Curious how to get this method in the Method Directive ?

An alternative would be the Data Directive but I need to keep it as a Last Bit …

There is this on the APInvGrp BO:

Erp.APInvGrp.PrePostGroupInvoices

Methods of Proc, Rpt, and Ice.Lib services are available only starting with 10.2.700 (to customize with BPM or to call with Invoke BO Method action).
Definitely, they are available in custom code.

This appears to be fulfilling my requirement (right now) until we fully tested.