code: public static RSAPublicKey buildPublicKey(String base64KeyData)
              throws NoSuchAlgorithmException, InvalidKeySpecException {
          byte[] keyData = Base64.getDecoder().decode(base64KeyData);
          return buildPublicKey(keyData);
      }
docs: Construct the RSA public key from a key string data.
  
  @param base64KeyData
  RSA public key in base64 (base64 of {@link RSAPublicKey#getEncoded()})
  @return
  @throws NoSuchAlgorithmException
  @throws InvalidKeySpecException