Anyone know how to add custom flags to RoundSync?

I know this is still tengentially related to rclone but I don't think it fits in the other categories.

I need to enable syncing of empty directories in RoundSync but looking at the github, it seems it's not yet a thing and with development put on maintenance mode, I don't think it'll come any time soon either. However, the developer said that one can just add the flag and recompile the app.

The thing is I don't know where to add this --create-empty-src-dirs flag. So if anyone can kindly point me to where in the source code I need to add this, I would really appreciate it.

I think I can work out how to compile it afterwards.