@Override
    public void streamHandler(IAsyncHandler<ISignalWriteStream> handler) {
        this.inboundStreamHandler = handler;
    }
@see io.apiman.gateway.engine.IApiRequestExecutor#streamHandler(io.apiman.gateway.engine.async.IAsyncHandler)
gateway/engine/core/src/main/java/io/apiman/gateway/engine/impl/ApiRequestExecutorImpl.java