private byte[] receiveResponseOrToken() throws IOException {
        if (netInBuffer == null) netInBuffer = new NetworkReceive(node);
        netInBuffer.readFrom(transportLayer);
        byte[] serverPacket = null;
        if (netInBuffer.complete()) {
            netInBuffer.payload().rewind();
            serverPacket = new byte[netInBuffer.payload().remaining()];
            netInBuffer.payload().get(serverPacket, 0, serverPacket.length);
            netInBuffer = null; // reset the networkReceive as we read all the data.
        }
        return serverPacket;
    }
Sends a SASL client token to server if required. This may be an initial token to start
SASL token exchange or response to a challenge from the server.
@return true if a token was sent to the server
clients/src/main/java/org/apache/kafka/common/security/authenticator/SaslClientAuthenticator.java