code: public Mac getMac(final @NotNull String alias) {
          try {
              final Key secretKey = keys.get(alias);
  
              Mac mac = Mac.getInstance(secretKey.getAlgorithm());
              mac.init(secretKey);
  
              return mac;
          } catch (NoSuchAlgorithmException | InvalidKeyException e) {
              throw new RuntimeException(e);
          }
      }
docs: Creates a new Message Authentication Code
  @param alias algorithm to use e.g.: HmacSHA256
  @return Mac implementation