code: public static byte[] base64ToBinary(String base64Value) throws IllegalArgumentException {
          Utils.require(base64Value.length() % 4 == 0,
                        "Invalid base64 value (must be a multiple of 4 chars): " + base64Value);
          return DatatypeConverter.parseBase64Binary(base64Value);
      }
docs: Convert (decode) the given Base64-encoded String to its binary form.
  
  @param base64Value               Base64-encoded string.
  @return                          Decoded binary value.
  @throws IllegalArgumentException If the given string is not a valid Base64 value.