code: public static String getUniqueId(String accessId) {
          Matcher m = matcher(accessId);
          if (m != null) {
              return m.group(3);
          }
          return null;
      }
docs: Given an accessId, extract the uniqueId.
  
  @param accessId
  @return The uniqueId for the accessId, or {@code null} if the accessId is invalid