java.lang.NullPointerException: null at springfox.documentation.spring.web.WebMvcPatternsRequestConditionWrapper.getPatterns(WebMvcPatternsRequestConditionWrapper.java:56)

Spring Boot 프로젝트에 swagger를 적용하려고 했으나 다음과 같은 문제가 발생했다.

org.springframework.context.ApplicationContextException: Failed to start bean 'documentationPluginsBootstrapper'; nested exception is java.lang.NullPointerException
	at org.springframework.context.support.DefaultLifecycleProcessor.doStart(DefaultLifecycleProcessor.java:181) ~[spring-context-5.3.23.jar:5.3.23]
	at org.springframework.context.support.DefaultLifecycleProcessor.access$200(DefaultLifecycleProcessor.java:54) ~[spring-context-5.3.23.jar:5.3.23]
	at org.springframework.context.support.DefaultLifecycleProcessor$LifecycleGroup.start(DefaultLifecycleProcessor.java:356) ~[spring-context-5.3.23.jar:5.3.23]
	at java.lang.Iterable.forEach(Iterable.java:75) ~[na:1.8.0_202]
	at org.springframework.context.support.DefaultLifecycleProcessor.startBeans(DefaultLifecycleProcessor.java:155) ~[spring-context-5.3.23.jar:5.3.23]
	at org.springframework.context.support.DefaultLifecycleProcessor.onRefresh(DefaultLifecycleProcessor.java:123) ~[spring-context-5.3.23.jar:5.3.23]
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:935) ~[spring-context-5.3.23.jar:5.3.23]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:586) ~[spring-context-5.3.23.jar:5.3.23]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:147) ~[spring-boot-2.7.4.jar:2.7.4]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:734) [spring-boot-2.7.4.jar:2.7.4]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:408) [spring-boot-2.7.4.jar:2.7.4]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:308) [spring-boot-2.7.4.jar:2.7.4]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) [spring-boot-2.7.4.jar:2.7.4]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1295) [spring-boot-2.7.4.jar:2.7.4]
	at com.junho.junhomepage.JunHomePageApplication.main(JunHomePageApplication.java:10) [main/:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_202]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_202]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_202]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_202]
	at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.7.4.jar:2.7.4]
Caused by: java.lang.NullPointerException: 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$3(Orderings.java:89) ~[springfox-spi-3.0.0.jar:3.0.0]
	at java.util.Comparator.lambda$comparing$77a9974f$1(Comparator.java:469) ~[na:1.8.0_202]
	at java.util.TimSort.countRunAndMakeAscending(TimSort.java:355) ~[na:1.8.0_202]
	at java.util.TimSort.sort(TimSort.java:220) ~[na:1.8.0_202]
	at java.util.Arrays.sort(Arrays.java:1512) ~[na:1.8.0_202]
	at java.util.ArrayList.sort(ArrayList.java:1462) ~[na:1.8.0_202]
	at java.util.stream.SortedOps$RefSortingSink.end(SortedOps.java:387) ~[na:1.8.0_202]
	at java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:1.8.0_202]
	at java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:1.8.0_202]
	at java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:1.8.0_202]
	at java.util.stream.Sink$ChainedReference.end(Sink.java:258) ~[na:1.8.0_202]
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482) ~[na:1.8.0_202]
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[na:1.8.0_202]
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[na:1.8.0_202]
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:1.8.0_202]
	at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[na:1.8.0_202]
	at springfox.documentation.spring.web.plugins.WebMvcRequestHandlerProvider.requestHandlers(WebMvcRequestHandlerProvider.java:81) ~[springfox-spring-webmvc-3.0.0.jar:3.0.0]
	at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[na:1.8.0_202]
	at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382) ~[na:1.8.0_202]
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) ~[na:1.8.0_202]
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[na:1.8.0_202]
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[na:1.8.0_202]
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:1.8.0_202]
	at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[na:1.8.0_202]
	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:178) ~[spring-context-5.3.23.jar:5.3.23]
	... 19 common frames omitted

 

SpringBoot 2.6버전에서 변경된 사항에서 문제점을 찾을 수 있다.

첫번째 문단을 보면 다음과 같이 설명하고있다.

The default strategy for matching request paths against registered Spring MVC handler mappings has changed from AntPathMatcher to PathPatternParser.

등록된 Spring MVC 핸들러 매핑에 대해 요청 경로를 일치시키는 기본 전략이 AntPathMatcher에서 PathPatternParser로 변경되었습니다.

기존 전략으로 변경하기 위해서(오류를 해결하기 위해서)는 application.properties에 다음 속성을 추가해주면 된다.

spring.mvc.pathmatch.matching-strategy=ant_path_matcher