code: public SpringApplicationBuilder child(Class<?>... sources) {
  		SpringApplicationBuilder child = new SpringApplicationBuilder();
  		child.sources(sources);
  
  		// Copy environment stuff from parent to child
  		child.properties(this.defaultProperties).environment(this.environment)
  				.additionalProfiles(this.additionalProfiles);
  		child.parent = this;
  
  		// It's not possible if embedded web server are enabled to support web contexts as
  		// parents because the servlets cannot be initialized at the right point in
  		// lifecycle.
  		web(WebApplicationType.NONE);
  
  		// Probably not interested in multiple banners
  		bannerMode(Banner.Mode.OFF);
  
  		// Make sure sources get copied over
  		this.application.addPrimarySources(this.sources);
  
  		return child;
  	}
docs: Create a child application with the provided sources. Default args and environment
  are copied down into the child, but everything else is a clean sheet.
  @param sources the sources for the application (Spring configuration)
  @return the child application builder