I made sure I enabled plugin and java in package.json, set it to true. Then I tried loading a page on the remote server with java applet, and I got an error message "couldn't load plug-in". Then I tried locally, by copying the plugin files into Resources/app.nw directory, on Mac OS. Still I got the same error. Same applet works in Firefox.
Btw, I could open sites with Flash, but not Java applets.
Thanks