code: public static byte[] decodeBase64(String base64) {
      if (base64 == null)
        throw new NullPointerException("Parameter 'base64' cannot be null.");
  
      String fixedBase64 = padBase64(base64);
      return Base64.getDecoder().decode(fixedBase64);
    }
docs: Decodes a base64-encoded string, padding out if necessary.
  
  @param base64
  The base64-encoded string to decode.
  @return A decoded version of {@code base64}.
  @throws NullPointerException
  If {@code base64} is {@code null}.