How to package java libraries

I am trying to modify the OpenCV package to be capable of outputting the jar (Allowing it to take the place of the libopencv-java package in the ubuntu repos). However, I have not been able to find any documentation on how to go about this. Most notably I don’t know where to place the jar. normally it would be expected in /usr/local/lib. I have not been able to figure out how you might link there. Has anyone done anything like this, is this dumb, or do I need to rethink my approach?

Any help is appreciated.

Note: in case you were wondering, gradle/maven is not suitable for my needs. The jar needs to be detectable by cmake (this is very niche).