code: public String decrypt(String data) {
  
          Objects.requireNonNull(data, "Data to be decrypted");
  
          if (!secretKeySpec.isPresent()) {
              return data;
          }
  
          // convert base64 encoded string to bytes
          byte[] decoded = Base64.decodeBase64(data);
          try {
              // decrypt bytes
              Cipher cipher = Cipher.getInstance(ALGORITHM);
              cipher.init(Cipher.DECRYPT_MODE, secretKeySpec.get());
              byte[] decrypted = cipher.doFinal(decoded);
  
              // convert bytes to string
              return new String(decrypted, StandardCharsets.UTF_8);
  
          } catch (InvalidKeyException ex) {
              logger.error(getHelperLogMessage(), ex);
              throw new RuntimeException(ex);
          } catch (GeneralSecurityException ex) {
              logger.error("Failed to decrypt data.", ex);
              return "";
          }
      }
docs: Decrypts data with secret key.
  
  @param data text to decrypt in base64 format
  @return decrypted text