Plugins get their own class loader, but there is not currently a way to put jars in this class loader except by declaring a jar to be a plugin. If the jar doesn't contain a plugin, however, a warning is printed.
This enhancement requests either removing the warning (not the preferred solution) or adding a new option, such as '-Xpluginscp' that allows specifying additional jars to be available to plugins. A patch is attached to demonstrate this.