code: public static boolean verifyLuhn (String key)
      {
          // If there is a non digit, or it is all zeros.
          if (StringUtil.isBlank(key) || key.matches(".*\\D.*") ||
              key.matches("^[0]+$")) {
              return false;
          }
  
          return (getLuhnRemainder(key) == 0);
      }
docs: Verify the key with the Luhn check.  If the key is all zeros,
  then the luhn check is true, but that is almost never what you want
  so explicitly check for zero and return false if it is.