PO_REQIMP_PKG User Hook Has Out Of Box Code - Will My Customizations Be Overwritten?

Per Doc ID 1080130.1 (and several other discussions) the way to update a requisition record that is coming from MRP to the PO requisition interface table po_requisitions_interface_all is to put your custom code in the user hook PO_REQIMP_PKG.POST_VALIDATE_USER_EXTENSIONS.

However, when I load the package this morning, I find out-of-the-box code in there from Oracle relating to Asia/Pacific Localizations.  Specifically it is looking at a profile option in that application to determine if auto-accounting should or should not be run.

I was very surprised to find out-of-the-box code in a user hook.