What I already did
I've already checked How to read and write excel file in java and Java Library to read Microsoft Excel files but they are all about the above libraries.
I have e java application for processing excel files. I implemented it with apache-poi but I was not able to sign it because xmlbeans.jar contains duplicated entries.
https://issues.apache.org/jira/browse/XMLBEANS-497
https://issues.apache.org/jira/browse/XMLBEANS-499
I saw the workaround in the second issue with patching the xmlbeans.jar but I don't like the idea of workarounds. I've already re-implemented the code with xlsx4j which can process .xlsx files and jexcel for .xls files.
Problem With two libraries the code is hard to maintain so I'm looking for another way to process .xlsx and .xls