Email to Purchase order creator with PDF attachment of PO after it is approved in flexible workflow.

[prasanth_kasturi]

Requirement is to send the PO creator with PDF attachment of PO after it is completely approved from Flexible workflow. I tried the below options

1) There is a Release event in the class CL_MM_PUR_WF_OBJECT_PO, but it is not triggered. Can someone help on how to get this event triggered. below is the trace log

2)  Use the Runtime class CL_MM_PUR_PO_FLEX_WFL of the workflow and write the code in the method RESULT_CALLBACK. Since we need to enhance standard class and also the PO is updated during this method, I feel it would be dicey to write logic here

Please suggest if there is a better method to achieve the requirement, we are on S/4 2020