I'm writing a Java (not Javascript) script library (not agent) in Code -> Script Libraries and would like to run this script from action button. Actually it works but I need to debug my Java code to complete my task. All manuals which I found in internet are regarding debugging of Java agents, not sure is it same setup or not for script libraries. Thank you.
There is no build-in debugger for debugging Java code called from LS2J.
You can include System.out.println() lines in your Java code and will see the output on server's console or on the client's Java console depending where code is running.
I suggest to create tests for your Java code with e.g. jUnit in Eclipse. There you can debug your code until it's running like expected and only then to use it from LS2J.
Be aware of some issues with LS2J. You can't use Java file resources for instance.