如何从通用MessageSource启动Spring Integration DSL Poller

@Configuration
@EnableIntegration
public class MyIntegrationConfig {

    @Bean
    public MessageSource<File> fileReadingMessageSource() {
        FileReadingMessageSource source = new FileReadingMessageSource();
        source.setDirectory(new File("/path/to/directory"));
        return source;
    }

    @Bean
    public IntegrationFlow myIntegrationFlow(MessageSource<File> messageSource) {
        return IntegrationFlows.from(messageSource, spec ->
                spec.poller(Pollers.fixedDelay(1000)))
                .transform(Transformers.fileToString())
                .handle(System.out::println)
                .get();
    }

    @Bean
    public IntegrationFlowContext integrationFlowContext() {
        return new IntegrationFlowContext();
    }

    @Bean
    public IntegrationFlowRegistration integrationFlowRegistration(IntegrationFlowContext flowContext,
                                                                   IntegrationFlow myIntegrationFlow) {
        return flowContext.registration(myIntegrationFlow)
                .addBean(myIntegrationFlow)
                .register();
    }

    public static void main(String[] args) {
        SpringApplication.run(MyIntegrationConfig.class, args);
    }
}