code: private static String escape(String input) {
          StringBuilder resultStr = new StringBuilder();
          for (char ch : input.toCharArray()) {
              if (isUnsafe(ch)) {
                  resultStr.append('%');
                  resultStr.append(toHex(ch / 16));
                  resultStr.append(toHex(ch % 16));
              } else {
                  resultStr.append(ch);
              }
          }
          return resultStr.toString();
      }
docs: '/' was removed from the unsafe list