How To Use the DrawDebugCanvas2DXXX function

Currently I need to Draw some 2D debug Object, I find Some Functions DrawDebugCanvas2DXXX(...)
But It needs UCanvas for Draw,So after some digging I found there’s a UCanvas* DebugCanvas in AHUD classes,
But it’s private and I can’t find a way to access The DebugCanvas in The AHUD.

So I want to ask How to use DrawDebugCanvas2DXXX(...) in general.

Thanks in advance.