Trying to use 3rd party java libraries: error unpacking while loading designer

I’d like to integrate this library in my project to read/write Excel files. I copied the following library files and dependencies

into the lib\core\common Ignition path, together with the pack200 processed files

The gateway starts with no error. But when I try to start the designer, I get this error message

and the Java Console reports the following exception

Any suggestion?

Thanks in advance, regards

After googling around I found that xmlbeans-2.6.0.jar has an issue and that is duplicated entries!
Applying what’s suggested here solved the issue.
Many thanks to Daniel!