docs: public static String extractHtmlBody(String content) {
  
          Matcher startMatcher = BODY_START_PATTERN.matcher(content);
          Matcher endMatcher = BODY_END_PATTERN.matcher(content);
  
          int start = 0;
          int end = content.length();
  
          if (startMatcher.find()) {
              start = startMatcher.end();
          }
  
          if (endMatcher.find(start)) {
              end = endMatcher.start();
          }
  
          return content.substring(start, end);
      }