HANA external library jar use

Hello there, experts.

I am trying to make an XS project in HANA which will use some of the classes and methods that can be found in a .jar file (it is an external library).

After input (CSV file) these classes and methods will do some calculations and present it to the user in UI (done in .xsjs file).

The question is: how do I access methods and classes of that .jar file? I have registered it as an external library, but I have no idea how to call it from my XS javascript source file. What is the easiest way?

Can you please help?

Thank you