code: @Override
  	public void toXML(final StringBuilder builder,
  			final ConfigVerification errors)
  	{
  
  		boolean sevenzip = controller.is7ZipEnabled();
  
  		if (sevenzip) {
  
  			String cmd;
  			builder.append("\t<externals>\r\n");
  
  			if (sevenzip) {
  				cmd = sevenZipPathField.getText();
  				if (cmd.length() == 0) {
  					errors.add(new ConfigItem(ConfigItemTypes.ERROR,
  							ConfigErrorKeys.PATH_NOT_SET,
  							"The path to the 7Zip executable" + " is missing."));
  				}
  
  				builder.append("\t\t<sevenzip>\"" + cmd + "\"</sevenzip>\r\n");
  			}
  
  			builder.append("\t</externals>\r\n");
  		}
  	}
docs: Adds the xml description of the panels content to the StringBuilder.
  Errors which occur during the xml transformation will be added to the
  ConfigVerification.
  
  @param builder
  Reference to a StringBuilder object
  @param errors
  Reference to the ConfigVerification object