code: public boolean validateSignature(@NonNull byte[] content, @NonNull String headerSignature) {
          final byte[] signature = generateSignature(content);
          final byte[] decodeHeaderSignature = Base64.getDecoder().decode(headerSignature);
          return MessageDigest.isEqual(decodeHeaderSignature, signature);
      }
docs: Validate signature.
  
  @param content Body of the http request in byte array.
  @param headerSignature Signature value from `X-LINE-Signature` HTTP header
  
  @return True if headerSignature matches signature of the content. False otherwise.