validate with hmac.java

private boolean isValidWebhook(String secret, String body, String timestamp, String headerSignature) {
      String computedSignature = getSignature(secret, body, timestamp);
      return headerSignature.equals(computedSignature);
  }


  String getSignature(String secret, String body, String timestamp) {
      SecretKeySpec signingKey = new SecretKeySpec(secret.getBytes(), HMAC);
      try {
          String signature = body + timestamp;
          Mac mac = Mac.getInstance(HMAC);
          mac.init(signingKey);
          byte[] rawHmac = mac.doFinal(signature.getBytes(StandardCharsets.UTF_8));
          return DatatypeConverter.printBase64Binary(rawHmac);
      } catch (Exception e) {
          LOGGER.error("Failed to generate Webhook Signature", e.getMessage());
          return null;
      }
  }