@UnstableApi
    public Consumer<? super ChannelPipeline> channelPipelineCustomizer() {
        return get(CHANNEL_PIPELINE_CUSTOMIZER);
    }
The {@link Consumer} that customizes the Netty {@link ChannelPipeline}.
This customizer is run right before {@link ChannelPipeline#connect(SocketAddress)}
is invoked by Armeria. This customizer is no-op by default.

<p>Note that usage of this customizer is an advanced
feature and may produce unintended side effects, including complete
breakdown. It is not recommended if you are not familiar with
Armeria and Netty internals.
core/src/main/java/com/linecorp/armeria/client/ClientFactoryOptions.java