code: public URLNormalizer secureScheme() {
          Matcher m = PATTERN_SCHEMA.matcher(url);
          if (m.find()) {
              String schema = m.group(1);
              if ("http".equalsIgnoreCase(schema)) {
                  url = m.replaceFirst(schema + "s$2");
              }
          }
          return this;
      }
docs: <p>Converts <code>http</code> scheme to <code>https</code>.</p>
  <code>http://www.example.com/ &rarr; https://www.example.com/</code>
  @return this instance