Integrating new feature dependency issue

I am working on integrating a new feature (PaSiMap) into Jalview and I need the org.apache.commons.math3.fitting.leastsquares package for that.
I have added the the classpath "org.apache.commons:commons-math3:3.6.1" into the dependencies section in the build.gradle, as suggested in the maven repo.
When I want to import the package in my source file, I get the error: "package org.apache.commons.math3.fitting.leastsquares" does not exist.

How do I make sure the package is available for my project?