I have had a similar error: Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: org/apache/commons/lang3/ObjectUtils

My solution was to add from https://commons.apache.org/proper/commons-lang/download_lang.cgi the file commons-lang3-3.17.0.jar to the build path. This file is located within the downloaded ZIP file.

I am using

• Eclipse EE, 2024-09 (4.33.0)
• OpenCSV 5.9 from https://sourceforge.net/projects/opencsv/

cheers