"Cannot unload a system plugin"); }
"Cannot unload a system plugin: "+pluginId); }
    public synchronized void unloadPlugin(String pluginId)            throws PluginException {	    final SecurityManager sm = System.getSecurityManager();	    if (sm != null) {	        sm.checkPermission(PluginSecurityConstants.UNLOAD_PERM);	    }        final PluginDescriptorModel descr = (PluginDescriptorModel)getPluginDescriptor(pluginId);        if (descr != null) {            if (descr.isSystemPlugin()) { throw new PluginException(                    "Cannot unload a system plugin"); }                        // Unload all plugins that depend on this plugin            final ArrayList descriptors = new ArrayList(descriptorMap.values());            for (Iterator i = descriptors.iterator(); i.hasNext();) {                final PluginDescriptor dep = (PluginDescriptor) i.next();                if (dep.depends(pluginId)) {                	unloadPlugin(dep.getId());                }            }            // Now remove it            descr.unresolve(this);        }    }