code: public static String createLanguageHeader() {
  
          String header;
  
          // get the default accept-language header value
          List<Locale> defaultLocales = OpenCms.getLocaleManager().getDefaultLocales();
          Iterator<Locale> i = defaultLocales.iterator();
          header = "";
          while (i.hasNext()) {
              Locale loc = i.next();
              header += loc.getLanguage() + ", ";
          }
          header = header.substring(0, header.length() - 2);
          return header;
      }
docs: Creates a value string for the HTTP Accept-Language header based on the default localed.<p>
  
  @return value string for the HTTP Accept-Language