Adding java custom classes to Ignition

General Discussion
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11

I have been trying to add the Apache POI jar to my gateway using this method, but when I run a button with the following code under it:

import org.apache.poi.xssf.usermodel.XSSFWorkbook

I get the following error:
Traceback (most recent call last):

File “event:mousePressed”, line 1, in

ImportError: No module named poi

Ignition v7.9.6 (b2018012914)
Java: Oracle Corporation 1.8.0_161

I have both the packed and normal jar file under the common folder for the Ignition gateway. I also restarted the gateway multiple times but nothing has changed.