Apache POI inside Docker container

I have created a simple Java application which generates an Excel file using Apache POI libraries (3.17). The code runs great while running in my machine as part of a Web application (Liberty).

I have to run this code inside a container. So I have created the docker image using this dockerfile:

FROM icr.io/ibm/liberty:20.0.0.6-wl-full

   # Add my app and config
   COPY --chown=1001:0  Home.war 			/config/apps/
   COPY --chown=1001:0  server.xml 			/config/
   COPY --chown=1001:0  server.env 			/config/

   # Add DB2 libraries
   COPY --chown=1001:0  Shared/DB2/ 		/config/myLib/DB2/

   # Add Common libraries
   COPY --chown=1001:0  Shared/Commons/	    /config/myLib/Commons/

   # Add Jackson libraries
   COPY --chown=1001:0  Shared/Jackson/ 	/config/myLib/Jackson/

   # Add POI libraries
   COPY --chown=1001:0  Shared/POI/ 		/config/myLib/POI/

The code runs fine inside the 'dockerized' Liberty until I reach the sentence which creates the workbook. Then the code execution totally freezes (at least the System.out after calling the constructor is not being displayed).

	XSSFWorkbook wb = new XSSFWorkbook();

I have tried different approaches to solve the error. Initially I was using (for historical reasons) SXSSFWorkbook instead of XSSFWorkbook. I have tried to create a temporary file and pass the file to the XSSFWorkbook constructor. No way.
I think this might be related with the use that POI is doing of temporary files. Or maybe a missing library but, as I said, the code is working fine when running on my computer.

I am not an expert in docker and maybe I am missing some basic configuration. Any ideas on why I am not capable of using POI? Thanks in advance.

Finally I discovered the problem. And I am posting here the solution just in case someone finds it useful.

There is no problem at all with using POI inside a docker container. I was declaring the POI libraries as shared libraries. But those POI libraries where not available to the application. No errors or exceptions. The application just freezes.

I tried to include the libraries inside the WAR and everything worked fine. So, definitely was a problem of visibility.

I switched the commonLibraryRef entry for a privateLibraryRef in my server.xml file and everything started to work as expected.

   <webApplication contextRoot="/" id="Home" location="Home.war" name="Home"> 
       	<application-bnd>

	...

    	</application-bnd>

       	<classloader privateLibraryRef="DB2,Commons,Jackson,POI"/>
    </webApplication>

    <library id="DB2">
    	<fileset dir="${server.config.dir}/myLib/DB2" id="DB2" includes="db2jcc4.jar db2jcc_license_cu.jar" scanInterval="5s"/>
    </library>
    <library id="Jackson">
    	<fileset dir="${server.config.dir}/myLib/Jackson" id="Jackson" includes="*.jar" scanInterval="5s"/>
    </library>
    <library id="Commons">
    	<fileset dir="${server.config.dir}/myLib/Commons" id="Commons" includes="*.jar" scanInterval="5s"/>
    </library>
    <library id="POI">
    	<fileset dir="${server.config.dir}/myLib/POI" id="POI" includes="*.jar" scanInterval="5s"/>
    </library>