WebConfig

@Configuration
public static class WebConfig extends WebMvcConfigurerAdapter {

	@Override
	public void configureAsyncSupport(AsyncSupportConfigurer configurer) {
		configurer.setDefaultTimeout(-1);
		configurer.setTaskExecutor(asyncTaskExecutor());
	}
		
	@Bean
	public AsyncTaskExecutor asyncTaskExecutor() {
		return new SimpleAsyncTaskExecutor("async");
	}
		
}