code: public String encode(long... numbers) {
          if (numbers.length == 0) {
              return "";
          }
  
          for (final long number : numbers) {
              if (number < 0) {
                  return "";
              }
              if (number > MAX_NUMBER) {
                  throw new IllegalArgumentException("number can not be greater than " + MAX_NUMBER + "L");
              }
          }
          return this._encode(numbers);
      }
docs: Encrypt numbers to string
  
  @param numbers the numbers to encrypt
  @return the encrypt string