Please make the customizers support `@Order`.

[zhujianxintian]

Currently, the internal org.springdoc.core.customizers.SpringDocCustomizers is as follows:

public class SpringDocCustomizers implements ApplicationContextAware, InitializingBean {

	/**
	 * The Open api customisers.
	 */
	private final Optional<Set<OpenApiCustomizer>> openApiCustomizers;

	/**
	 * The Operation customizers.
	 */
	private final Optional<Set<OperationCustomizer>> operationCustomizers;
	
	// ... other code ...
	
}

And this is where it is used:

public abstract class AbstractOpenApiResource extends SpecFilter {

	// ... other code ...
	
	protected OpenAPI getOpenApi(String serverBaseUrl, Locale locale) {
		this.reentrantLock.lock();
		try {
			final OpenAPI openAPI;
			final Locale finalLocale = selectLocale(locale);
			if (openAPIService.getCachedOpenAPI(finalLocale) == null || springDocConfigProperties.isCacheDisabled()) {

				// ... code ...

                // here
				openAPIService.getContext().getBeansOfType(OpenApiLocaleCustomizer.class).values().forEach(openApiLocaleCustomizer -> openApiLocaleCustomizer.customise(openAPI, finalLocale));
				springDocCustomizers.getOpenApiCustomizers().ifPresent(apiCustomizers -> apiCustomizers.forEach(openApiCustomizer -> openApiCustomizer.customise(openAPI)));

				// ... code ...
			}
			else {
				LOGGER.debug("Fetching openApi document from cache");
				openAPI = openAPIService.getCachedOpenAPI(finalLocale);
				openAPIService.updateServers(serverBaseUrl, openAPI);
			}
			return openAPI;
		}
		finally {
			SpringDocAnnotationsUtils.clearCache(operationParser.getJavadocProvider());
			this.reentrantLock.unlock();
		}
	}

	// ... other code ...

}

This approach does not support the @Order annotation.

Describe the solution you'd like

I would like to use ObjectProvider<T> instead of Optional<Set<T>>.

import org.springframework.beans.factory.ObjectProvider;

public class SpringDocCustomizers implements ApplicationContextAware, InitializingBean {

    /**
     * The Open api customisers.
     */
    private final ObjectProvider<OpenApiCustomizer> openApiCustomizers;

    /**
     * The Operation customizers.
     */
    private final ObjectProvider<OperationCustomizer> operationCustomizers;

    // ... other code ...

}

public abstract class AbstractOpenApiResource extends SpecFilter {

	// ... other code ...
	
	protected OpenAPI getOpenApi(String serverBaseUrl, Locale locale) {
		this.reentrantLock.lock();
		try {
			final OpenAPI openAPI;
			final Locale finalLocale = selectLocale(locale);
			if (openAPIService.getCachedOpenAPI(finalLocale) == null || springDocConfigProperties.isCacheDisabled()) {

				// ... code ...

                // here
                openAPIService.getContext().getBeanProvider(OpenApiLocaleCustomizer.class).orderedStream().forEach(customizer -> customizer.customise(openAPI, finalLocale));
                springDocCustomizers.getOpenApiCustomizers().orderedStream().forEach(customizer -> customizer.customise(openAPI));

				// ... code ...
			}
			else {
				LOGGER.debug("Fetching openApi document from cache");
				openAPI = openAPIService.getCachedOpenAPI(finalLocale);
				openAPIService.updateServers(serverBaseUrl, openAPI);
			}
			return openAPI;
		}
		finally {
			SpringDocAnnotationsUtils.clearCache(operationParser.getJavadocProvider());
			this.reentrantLock.unlock();
		}
	}

	// ... other code ...

}

This way, Spring's built-in .orderedStream() can be used to handle the ordering of @Order.

Otherwise, the execution order cannot be guaranteed, because I want to execute the following code after SpringDocSecurityConfiguration.SpringSecurityLoginEndpointConfiguration#springSecurityLoginEndpointCustomizer:

Add example values to the default login endpoint.

@Bean
// Set the lowest priority, execute last, to ensure it runs after SpringDocSecurityConfiguration.SpringSecurityLoginEndpointConfiguration#springSecurityLoginEndpointCustomizer
// Otherwise the login endpoint cannot be found
@Order
OpenApiCustomizer springSecurityLoginEndpointSchemaCustomizer(ApplicationContext applicationContext) {
    FilterChainProxy filterChainProxy = applicationContext.getBean(AbstractSecurityWebApplicationInitializer.DEFAULT_FILTER_NAME, FilterChainProxy.class);
    return openAPI -> {
        for (SecurityFilterChain filterChain : filterChainProxy.getFilterChains()) {
            Optional<UsernamePasswordAuthenticationFilter> optionalFilter =
                    filterChain.getFilters().stream()
                            .filter(UsernamePasswordAuthenticationFilter.class::isInstance)
                            .map(UsernamePasswordAuthenticationFilter.class::cast)
                            .findAny();
            if (optionalFilter.isPresent()) {
                UsernamePasswordAuthenticationFilter usernamePasswordAuthenticationFilter = optionalFilter.get();

                try {
                    RequestMatcher requestMatcher = (RequestMatcher) FieldUtils.readField(
                            usernamePasswordAuthenticationFilter,
                            "requiresAuthenticationRequestMatcher",
                            true
                    );

                    if (requestMatcher instanceof PathPatternRequestMatcher pathPatternRequestMatcher) {
                        String loginPath = getPath(pathPatternRequestMatcher);

                        Map.Entry<String, PathItem> loginPathEntry = openAPI.getPaths().entrySet().stream().filter(entry -> entry.getKey().equals(loginPath)).findAny().orElse(null);

                        if (loginPathEntry == null) {
                            return;
                        }

                        PathItem value = loginPathEntry.getValue();

                        value.readOperations().forEach(operation -> {
                            // Add example values to the login operation
                        });
                    }
                }
                catch (IllegalAccessException | ClassCastException e) {
                    // Exception escaped
                    log.trace(e.getMessage());
                }
            }
        }
    };
}