Spring 5.3/Spring Boot 2.4 support

If you enable the new PathPatternParser (https://spring.io/blog/2020/06/30/url-matching-with-pathpattern-in-spring-mvc), springfox fails with an NPE

Details

org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:185) ~[spring-context-5.3.0-M1.jar:5.3.0-M1]
	at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:53) ~[spring-context-5.3.0-M1.jar:5.3.0-M1]
	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:360) ~[spring-context-5.3.0-M1.jar:5.3.0-M1]
	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:158) ~[spring-context-5.3.0-M1.jar:5.3.0-M1]
	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:122) ~[spring-context-5.3.0-M1.jar:5.3.0-M1]
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:913) ~[spring-context-5.3.0-M1.jar:5.3.0-M1]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:570) ~[spring-context-5.3.0-M1.jar:5.3.0-M1]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.4.0-M1.jar:2.4.0-M1]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) ~[spring-boot-2.4.0-M1.jar:2.4.0-M1]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) ~[spring-boot-2.4.0-M1.jar:2.4.0-M1]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.4.0-M1.jar:2.4.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.4.0-M1.jar:2.4.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) ~[spring-boot-2.4.0-M1.jar:2.4.0-M1]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.4.0-M1.jar:2.4.0-M1]
	at me.minidigger.hangar.HangarApplication.main(HangarApplication.java:10) ~[classes/:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
	at java.base/java.lang.reflect.Method.invoke(Method.java:564) ~[na:na]
	at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) ~[spring-boot-devtools-2.4.0-M1.jar:2.4.0-M1]
Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.web.servlet.mvc.condition.PatternsRequestCondition.getPatterns()" because "this.condition" is null
	at springfox.documentation.spring.web.WebMvcPatternsRequestConditionWrapper.getPatterns(WebMvcPatternsRequestConditionWrapper.java:56) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
	at springfox.documentation.RequestHandler.sortedPaths(RequestHandler.java:113) ~[springfox-core-3.0.0.jar:3.0.0]
	at springfox.documentation.spi.service.contexts.Orderings.lambda$byPatternsCondition$3(Orderings.java:89) ~[springfox-spi-3.0.0.jar:3.0.0]
	at java.base/java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469) ~[na:na]
	at java.base/java.util.TimSort.binarySort(TimSort.java:296) ~[na:na]
	at java.base/java.util.TimSort.sort(TimSort.java:239) ~[na:na]
	at java.base/java.util.Arrays.sort(Arrays.java:1306) ~[na:na]
	at java.base/java.util.ArrayList.sort(ArrayList.java:1720) ~[na:na]
	at java.base/java.util.stream.SortedOps$RefSortingSink.end(SortedOps.java:392) ~[na:na]
	at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
	at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
	at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
	at java.base/java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:485) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
	at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:81) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
	at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195) ~[na:na]
	at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1624) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[na:na]
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913) ~[na:na]
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:na]
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578) ~[na:na]
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.withDefaults(AbstractDocumentationPluginsBootstrapper.java:107) ~[springfox-spring-web-3.0.0.jar:3.0.0]
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.buildContext(AbstractDocumentationPluginsBootstrapper.java:91) ~[springfox-spring-web-3.0.0.jar:3.0.0]
	at springfox.documentation.spring.web.plugins.AbstractDocumentationPluginsBootstrapper.bootstrapDocumentationPlugins(AbstractDocumentationPluginsBootstrapper.java:82) ~[springfox-spring-web-3.0.0.jar:3.0.0]
	at springfox.documentation.spring.web.plugins.DocumentationPluginsBootstrapper.start(DocumentationPluginsBootstrapper.java:100) ~[springfox-spring-web-3.0.0.jar:3.0.0]
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:182) ~[spring-context-5.3.0-M1.jar:5.3.0-M1]
	... 19 common frames omitted

I thought it was fixed by this line https://github.com/springfox/springfox/blob/master/springfox-spring-webmvc/src/main/java/springfox/documentation/spring/web/WebMvcRequestHandler.java#L83

-        requestMapping.getPatternsCondition());
+        requestMapping.getActivePatternsCondition());

but I couldn’t get this to work in 5 minutes, this prolly needs larger refactors.

for reference: https://github.com/spring-projects/spring-framework/blob/b572f7618f01897b611a47376c538b88be4dff80/spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/RequestMappingInfo.java#L219

edit: if you face this issue, you should consider upgrading to springdoc since this lib seems dead: https://springdoc.org/migrating-from-springfox.html

[hhhhsw]

1. set spring.mvc.pathmatch.matching-strategy: ant_path_matcher in application.properties
2. add this bean

@Bean
public WebMvcEndpointHandlerMapping webEndpointServletHandlerMapping(WebEndpointsSupplier webEndpointsSupplier, ServletEndpointsSupplier servletEndpointsSupplier, ControllerEndpointsSupplier controllerEndpointsSupplier, EndpointMediaTypes endpointMediaTypes, CorsEndpointProperties corsProperties, WebEndpointProperties webEndpointProperties, Environment environment) {
        List<ExposableEndpoint<?>> allEndpoints = new ArrayList();
        Collection<ExposableWebEndpoint> webEndpoints = webEndpointsSupplier.getEndpoints();
        allEndpoints.addAll(webEndpoints);
        allEndpoints.addAll(servletEndpointsSupplier.getEndpoints());
        allEndpoints.addAll(controllerEndpointsSupplier.getEndpoints());
        String basePath = webEndpointProperties.getBasePath();
        EndpointMapping endpointMapping = new EndpointMapping(basePath);
        boolean shouldRegisterLinksMapping = this.shouldRegisterLinksMapping(webEndpointProperties, environment, basePath);
        return new WebMvcEndpointHandlerMapping(endpointMapping, webEndpoints, endpointMediaTypes, corsProperties.toCorsConfiguration(), new EndpointLinksResolver(allEndpoints, basePath), shouldRegisterLinksMapping, null);
    }


private boolean shouldRegisterLinksMapping(WebEndpointProperties webEndpointProperties, Environment environment, String basePath) {
        return webEndpointProperties.getDiscovery().isEnabled() && (StringUtils.hasText(basePath) || ManagementPortType.get(environment).equals(ManagementPortType.DIFFERENT));
    }

[maxxedev]

Here is another work-around:

1. revert matching strategy spring.mvc.pathmatch.matching-strategy to ant-path-matcher
2. add this bean to your app:

@Bean
public static BeanPostProcessor springfoxHandlerProviderBeanPostProcessor() {
    return new BeanPostProcessor() {

        @Override
        public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
            if (bean instanceof WebMvcRequestHandlerProvider || bean instanceof WebFluxRequestHandlerProvider) {
                customizeSpringfoxHandlerMappings(getHandlerMappings(bean));
            }
            return bean;
        }

        private <T extends RequestMappingInfoHandlerMapping> void customizeSpringfoxHandlerMappings(List<T> mappings) {
            List<T> copy = mappings.stream()
                    .filter(mapping -> mapping.getPatternParser() == null)
                    .collect(Collectors.toList());
            mappings.clear();
            mappings.addAll(copy);
        }

        @SuppressWarnings("unchecked")
        private List<RequestMappingInfoHandlerMapping> getHandlerMappings(Object bean) {
            try {
                Field field = ReflectionUtils.findField(bean.getClass(), "handlerMappings");
                field.setAccessible(true);
                return (List<RequestMappingInfoHandlerMapping>) field.get(bean);
            } catch (IllegalArgumentException | IllegalAccessException e) {
                throw new IllegalStateException(e);
            }
        }
    };
}