PostProcessBuild failed to copy file

Hi,

I am quite confused about that case.. here it is:
I got a custom iOS plugin(.h + .m files) and .plist file for configuration. The problem is that I can't attach that .plist file.
I tried to use PBXProject - .plist reference has been attached to project, but the file missing. That wasn't copied at all. Also I have tried to use FileUtils using absolute path, and that worked only if to use project/build paths (do not put .plist file to any directory)

Attaching code with examples...

PostProcessBuild failed to copy file