private String getAvailablePluginsUpdateRequest() {
        Element xmlRequest = docFactory.createDocument().addElement("available");
        // Add locale so we can get current name and description of plugins
        Element locale = xmlRequest.addElement("locale");
        locale.addText(JiveGlobals.getLocale().toString());
        return xmlRequest.asXML();
    }
Returns the plugin update or {@code null} if the plugin is up to date.

@param pluginName     the name of the plugin (as described in the meta-data).
@param currentVersion current version of the plugin that is installed.
@return the plugin update or null if the plugin is up to date.
xmppserver/src/main/java/org/jivesoftware/openfire/update/UpdateManager.java