anchor.diff:  	private static class MyCustomizer implements EmbeddedServletContainerCustomizer {
   
   		@Override
  -		public void customize(ConfigurableEmbeddedServletContainer factory) {
  -            factory.addErrorPages(new ErrorPage(HttpStatus.BAD_REQUEST, "/400"));
  +		public void customize(ConfigurableEmbeddedServletContainer container) {
  +            container.addErrorPages(new ErrorPage(HttpStatus.BAD_REQUEST, "/400"));
   		}
   
   	}
  
positive.code: If you need to configure your embdedded servlet container programmatically you can register
  a Spring bean that implements the `EmbeddedServletContainerCustomizer` interface.
  `EmbeddedServletContainerCustomizer` provides access to the
  `ConfigurableEmbeddedServletContainerFactory` which includes numerous customization
  setter methods.
  
  [source,java,indent=0]
  ----
  
negative.code: 
  
  [[boot-features-customizing-configurableembeddedservletcontainerfactory-directly]]
  ===== Customizing ConfigurableEmbeddedServletContainer directly
  If the above customization techniques are too limited, you can register the
  `TomcatEmbeddedServletContainerFactory` or `JettyEmbeddedServletContainerFactory` bean
  yourself.
  