RequestHandlerProvider evaluated too early for Spring-Integration

Version 3.0.0-SNAPSHOT

Issue Kind: Bug Report (possibly)

Following https://github.com/springfox/springfox/issues/550 I have started to implement support for spring-integration in spring-boot 2.

I have tried to follow the approach taken by the WebFlux support by adding a RequestHandlerProvider plugin which uses the IntegrationRequestMappingHandlerMapping internally.

The Springfox DocumentationPluginsBootstrapper evaluates my RequestHandlerProvider, but at that point, the mappingRegistry of the IntegrationRequestMappingHandlerMapping is still empty. The reason is that the IntegrationRequestMappingHandlerMapping purposefully postpones the call to detectHandlerMethods, it happens not in afterPropertiesSet, but on ContextRefreshedEvent. This code is from IntegrationRequestMappingHandlerMapping:

@Override
public void afterPropertiesSet() {
	// No-op in favor of onApplicationEvent
}

/**
 * {@link HttpRequestHandlingEndpointSupport}s may depend on auto-created
 * {@code requestChannel}s, so MVC Handlers detection should be postponed
 * as late as possible.
 * @see RequestMappingHandlerMapping#afterPropertiesSet()
 */
@Override
public void onApplicationEvent(ContextRefreshedEvent event) {
	if (!this.initialized.getAndSet(true)) {
		super.afterPropertiesSet();
	}
}

It seems that DocumentationPluginsBootstrapper wrongly assumes it can rely on all RequestHandlerProviders to be initialized when it collects the request handlers. It returns Integer.MAX_VALUE in getPhase to ensure this, but apparently that is not enough.

One possibility might be to change DocumentationPluginsBootstrapper so that it initializes last on ContextRefreshedEvent (with very low precedence) or something else which is more appropriate.

What do you think?

[dschulten]

PR: https://github.com/springfox/springfox/pull/2793, closing

[dschulten]

The usual swagger annotations are a challenge, since there is no code to annotate in SI. I am considering to use spring-restdoc or a similar approach: mvc or webclient tests document inputs and outputs as documentation snippets. They generate adoc snippets. Is there a plugin to include external documentation fragments already?