code: @Override
      public String decryptAES(String value, String privateKey) {
          try {
              byte[] raw = privateKey.getBytes(UTF_8);
              SecretKeySpec skeySpec = new SecretKeySpec(raw, AES_ECB_ALGORITHM);
              Cipher cipher = Cipher.getInstance(AES_ECB_ALGORITHM);
              cipher.init(Cipher.DECRYPT_MODE, skeySpec);
              return new String(cipher.doFinal(decodeHex(value)), Charsets.UTF_8);
          } catch (NoSuchAlgorithmException | NoSuchPaddingException |
                  InvalidKeyException | BadPaddingException | IllegalBlockSizeException e) {
              throw new IllegalStateException(e);
          }
      }
docs: Decrypt a String with the standard AES encryption (using the ECB mode). Private key must have a length of 16
  bytes.
  
  @param value      An hexadecimal encrypted string
  @param privateKey The key used to encrypt
  @return The decrypted String