App refused due to undisclosed API

Today an update to an App I have on the App store was refused for the following reason;

Your app uses or references the following non-public API(s):

: OBJC_IVAR_$_NSEPSImageRep._pdfImageRep

The use of non-public APIs is not permitted on the App Store as it can lead to a poor user experience should these APIs change.

Can anyone tell me what is using that API? Could it be a MonkeyBread Software plugin?
How can I determine what uses it?

I fixed that here already.

@Christian Schmitz : I should have known that :slight_smile: From which plugin version onward is it fixed?

I put newer plugins in the dropbox:

upload may take a while for all 66 plugins.