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The solution for me was to close NetBeans, clear the NetBeans cache and restart NetBeans. I was using version 8.0 and the location of the cache for me is:
~/.cache/netbeans/8.0/
I deleted everything in the folder and on the next run everything was fine.
i add all of them: mina-code, mysql-connector-java-bin, slf4j-api, slf4j-jdk14FCode, likely you havent added apache mina to your required library.
Do you have discord? I'm happy to help.