Track add-friend source on follow event

When a user adds my LINE official account as a friend from an QR code (with add-friend url http://nav.cx/13FoWtu ), how can I track the source from this QR code in webhook server. I assume the QR code can have different utm_source in url like: banner(http://nav.cx/13FoWtu?utm_source=banner) or FB (http://nav.cx/13FoWtu?utm_source=facebook) I want to get the utm_source value in webhook server when a follow event fired.