MetaTransactions and Web3j

Support
1

I successfully run the Openzeppelin workshop about meta-transactions: https://github.com/OpenZeppelin/workshops/tree/master/25-defender-metatx-api

I'm now trying to translate it to Java using the Web3j library. I'm encountering issues with the function's signature. This is what I've do so far:

public TransactionReceipt emitRegistry(Web3j web3j, String signerPrivateKey, String senderPrivateKey, String registryContractAddress, String forwardContractAddress, String addressToSendGreetingsTo) throws Exception {
        final Credentials signerCredentials = Credentials.create(signerPrivateKey);
        final Credentials senderCredentials = Credentials.create(senderPrivateKey);

        BigInteger gasPrice = web3j.ethGasPrice().send().getGasPrice();
        BigInteger gasLimit = DefaultGasProvider.GAS_LIMIT;

        final Function createRegistryfunction = new Function(
                FUNC_CREATEREGISTRY,
                List.of(new Address(160, addressToSendGreetingsTo)),
                Collections.emptyList());
        byte[] encodedFunction = FunctionEncoder.encode(createRegistryfunction).getBytes(StandardCharsets.UTF_8);

        // Send the signed transaction to the network
        Sign.SignatureData signature = Sign.signMessage(encodedFunction, signerCredentials.getEcKeyPair());
        byte[] signatureInBytes = new byte[65];
        System.arraycopy(signature.getR(), 0, signatureInBytes, 0, 32);
        System.arraycopy(signature.getS(), 0, signatureInBytes, 32, 32);
        System.arraycopy(signature.getV(), 0, signatureInBytes, 64, 1);

        MinimalForwarder minimalForwarder = MinimalForwarder.load(forwardContractAddress, web3j, senderCredentials, new DefaultGasProvider());
        BigInteger nonce = minimalForwarder.getNonce(signerCredentials.getAddress()).send();

        // create forward request
        MinimalForwarder.ForwardRequest forwardRequest = new MinimalForwarder.ForwardRequest(
                signerCredentials.getAddress(),
                registryContractAddress,
                BigInteger.ZERO,
                gasLimit,
                nonce,
                encodedFunction
        );

        return minimalForwarder.execute(forwardRequest, signatureInBytes, gasLimit.add(gasPrice)).send();
}

But I always receive the message Revert reason: MinimalForwarder: signature does not match request.

Did anyone tried the same?

Thanks