code: public static void finalizeHandler(Bootstrap b,
  			ChannelOperations.OnSetup opsFactory,
  			ConnectionObserver listener) {
  		Objects.requireNonNull(b, "bootstrap");
  		Objects.requireNonNull(listener, "listener");
  
  		BootstrapPipelineHandler pipeline = null;
  		ChannelHandler handler = b.config().handler();
  		if (handler instanceof BootstrapPipelineHandler){
  			pipeline = (BootstrapPipelineHandler) handler;
  		}
  
  
  		if (pipeline != null) {
  			PipelineConfiguration pipelineConfiguration;
  			for (int i = 0; i < pipeline.size(); i++) {
  				pipelineConfiguration = pipeline.get(i);
  				if (pipelineConfiguration.deferredConsumer != null) {
  					pipeline.set(i,
  							new PipelineConfiguration(
  									pipelineConfiguration.deferredConsumer.apply(b),
  									pipelineConfiguration.name));
  				}
  			}
  		}
  
  		b.handler(new BootstrapInitializerHandler(pipeline, opsFactory, listener));
  	}
docs: Finalize a bootstrap pipeline configuration by turning it into a
  {@link ChannelInitializer} to safely initialize each child channel.
  
  @param b a bootstrap
  @param opsFactory an operation factory
  @param listener a connection observer