code: private static byte[] getAlphabet(int options) {
          if ((options & URL_SAFE) == URL_SAFE) {
              return _URL_SAFE_ALPHABET;
          } else if ((options & ORDERED) == ORDERED) {
              return _ORDERED_ALPHABET;
          } else {
              return _STANDARD_ALPHABET;
          }
      }
docs: Returns one of the _SOMETHING_ALPHABET byte arrays depending on the options specified. It's possible, though silly, to
  specify ORDERED <b>and</b> URLSAFE in which case one of them will be picked, though there is no guarantee as to which one
  will be picked.