public Plc4xEmbeddedChannel flushOutbound() {
        if (checkOpen(true)) {
            flushOutbound0();
        }
        checkException(voidPromise());
        return this;
    }
Flushes the outbound of this {@link Channel}. This method is conceptually equivalent to {@link #flush()}.

@see #flushInbound()
plc4j/transports/test/src/main/java/io/netty/channel/embedded/Plc4xEmbeddedChannel.java