#vulnerable code 
                                public byte[] getChannelConfigurationBytes() throws TransactionException {
        try {
            final Block configBlock = getConfigBlock(getShuffledPeers());

            Envelope envelopeRet = Envelope.parseFrom(configBlock.getData().getData(0));

            Payload payload = Payload.parseFrom(envelopeRet.getPayload());

            ConfigEnvelope configEnvelope = ConfigEnvelope.parseFrom(payload.getData());
            return configEnvelope.getConfig().toByteArray();

        } catch (Exception e) {
            throw new TransactionException(e);
        }

    } 
                            #location 3 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                public byte[] getChannelConfigurationBytes() throws InvalidArgumentException, TransactionException {
        return getChannelConfigurationBytes(client.getUserContext());
    }