code: public static CmsXmlSitemapGenerator createSitemapGenerator(String className, String folderRootPath)
      throws CmsException {
  
          if (CmsStringUtil.isEmptyOrWhitespaceOnly(className)) {
              className = (String)(OpenCms.getRuntimeProperty(PARAM_DEFAULT_SITEMAP_GENERATOR));
          }
          if (CmsStringUtil.isEmptyOrWhitespaceOnly(className)) {
              className = CmsXmlSitemapGenerator.class.getName();
          }
          try {
              Class<? extends CmsXmlSitemapGenerator> generatorClass = Class.forName(className).asSubclass(
                  CmsXmlSitemapGenerator.class);
              Constructor<? extends CmsXmlSitemapGenerator> constructor = generatorClass.getConstructor(String.class);
              CmsXmlSitemapGenerator generator = constructor.newInstance(folderRootPath);
              return generator;
          } catch (Exception e) {
              LOG.error(
                  "Could not create configured sitemap generator " + className + ", using the default class instead",
                  e);
              return new CmsXmlSitemapGenerator(folderRootPath);
          }
      }
docs: Creates an XML sitemap generator instance given a class name and the root path for the sitemap.<p>
  
  @param className the class name of the sitemap generator (may be null for the default
  @param folderRootPath the root path of the start folder for the sitemap
  @return the sitemap generator instance
  
  @throws CmsException if something goes wrong