code: public static Map<String, String> extractMetatags(String html) {
          Map<String, String> metatagsMap = new HashMap<>();
                  
          Matcher m = METATAG_PATTERN.matcher(html);
          while (m.find()) {
              if(m.groupCount()==2) {
                  String name = m.group(1);
                  String content = m.group(2);
                  metatagsMap.put(clear(name), clear(content));
              }
          }
          return metatagsMap;
      }
docs: Extracts the meta tags from an HTML page and returns them in a map.
  
  @param html
  @return