Making it easier to replace beans that are auto-configured by SpringBootBatchConfiguration about spring-boot

[wilkinsona]

I think we could achieve this by having SpringBootBatchConfiguration override the @Bean methods that are declared in DefaultBatchConfiguration and marking them as @ConditionalOnMissingBean. This would be similar to what we've done for some Spring MVC-related beans:

spring-boot/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java

Lines 444 to 470 in 7c4ce13

	@Override
	@Bean
	@ConditionalOnMissingBean(name = DispatcherServlet.LOCALE_RESOLVER_BEAN_NAME)
	public LocaleResolver localeResolver() {
	if (this.webProperties.getLocaleResolver() == WebProperties.LocaleResolver.FIXED) {
	return new FixedLocaleResolver(this.webProperties.getLocale());
	}
	AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
	localeResolver.setDefaultLocale(this.webProperties.getLocale());
	return localeResolver;
	}
	@Override
	@Bean
	@ConditionalOnMissingBean(name = DispatcherServlet.THEME_RESOLVER_BEAN_NAME)
	@Deprecated(since = "3.0.0", forRemoval = false)
	@SuppressWarnings("deprecation")
	public org.springframework.web.servlet.ThemeResolver themeResolver() {
	return super.themeResolver();
	}
	@Override
	@Bean
	@ConditionalOnMissingBean(name = DispatcherServlet.FLASH_MAP_MANAGER_BEAN_NAME)
	public FlashMapManager flashMapManager() {
	return super.flashMapManager();
	}