@Override
    public String getProtocol() {
        return getConfiguration().getProtocol();
    }
Returns the version of the Guacamole protocol associated with the
Guacamole connection negotiated by this ConfiguredGuacamoleSocket. This
version is the lowest version common to both ConfiguredGuacamoleSocket
and the relevant Guacamole proxy instance (guacd).

@return
    The protocol version that this ConfiguredGuacamoleSocket will use to
    communicate with guacd.
guacamole-common/src/main/java/org/apache/guacamole/protocol/ConfiguredGuacamoleSocket.java