code: public URLNormalizer upperCaseEscapeSequence() {
          if (url.contains("%")) {
              StringBuffer sb = new StringBuffer();
              Matcher m = PATTERN_PERCENT_ENCODED_CHAR.matcher(url);
              while (m.find()) {
                  m.appendReplacement(sb, m.group(1).toUpperCase());
              }
              url = m.appendTail(sb).toString();
          }
          return this;
      }
docs: Converts letters in URL-encoded escape sequences to upper case.<p>
  <code>http://www.example.com/a%c2%b1b &rarr;
  http://www.example.com/a%C2%B1b</code>
  @return this instance