How do I find the calling customer exit clause in HANA S/4

Sombody created a customer exit. It's name is EXIT_SAPLMGMU_001. So according to below tutorial https://wiki.scn.sap.com/wiki/pages/viewpage.action?pageId=107774353, I should open function SAPLMGMU in SE38 and looking for 'CALL CUSTOMER-FUNCTION XXX'. But I can't find any CALL in this function, and instead it contains a lot of include. Is this because my system is HANA S/4 and the tutorial is R/3? Then where is the call transaction location? Thx.