NullPointerException thrown in SchemaUtils

[pwannenmacher]

Describe the bug

I have a RestController method that looks like this:

// de.frachtwerk.essencium.backend.controller.AbstractUserController (see https://github.com/Frachtwerk/essencium-backend)
  @Override
  @PutMapping(value = "/{id}")
  @Parameter(
      in = ParameterIn.PATH,
      name = "id",
      description = "ID of the user to update",
      required = true,
      content = @Content(schema = @Schema(type = "integer")))
  @Secured({BasicApplicationRight.Authority.USER_UPDATE})
  @Operation(summary = "Update a user by passing the entire object")
  public REPRESENTATION update(
      @PathVariable("id") @NotNull final ID id,
      @Valid @RequestBody @NotNull final USERDTO user,
      @Spec(path = "id", pathVars = "id", spec = Equal.class) @Parameter(hidden = true) SPEC spec) {
    return super.update(id, user, spec);
  }

In this case, the generics are:

• ID -> Long
• USERDTO -> a suitable implementation of an abstract class
• SPEC -> a suitable implementation of Specification

The application starts and performs its service correctly.
Currently, when calling the openAPI endpoint at /v3/api-docs, the following NullPointerException is thrown:

Cannot invoke "io.swagger.v3.oas.models.media.Schema.getSpecVersion()" because "schema" is null
java.lang.NullPointerException: Cannot invoke "io.swagger.v3.oas.models.media.Schema.getSpecVersion()" because "schema" is null
	at org.springdoc.core.utils.SchemaUtils.applyValidationsToSchema(SchemaUtils.java:261)
	at org.springdoc.core.service.AbstractRequestService.applyBeanValidatorAnnotations(AbstractRequestService.java:620)
	at org.springdoc.core.service.AbstractRequestService.build(AbstractRequestService.java:331)
	at org.springdoc.api.AbstractOpenApiResource.calculatePath(AbstractOpenApiResource.java:623)
	at org.springdoc.api.AbstractOpenApiResource.calculatePath(AbstractOpenApiResource.java:815)
	at org.springdoc.webmvc.api.OpenApiResource.lambda$calculatePath$13(OpenApiResource.java:227)
	at java.base/java.util.Optional.ifPresent(Optional.java:178)
	at org.springdoc.webmvc.api.OpenApiResource.calculatePath(OpenApiResource.java:208)
	at org.springdoc.webmvc.api.OpenApiResource.lambda$getPaths$4(OpenApiResource.java:178)
	at java.base/java.util.Optional.ifPresent(Optional.java:178)
	at org.springdoc.webmvc.api.OpenApiResource.getPaths(OpenApiResource.java:152)
	at org.springdoc.api.AbstractOpenApiResource.getOpenApi(AbstractOpenApiResource.java:371)
	at org.springdoc.webmvc.api.OpenApiResource.openapiJson(OpenApiResource.java:127)
	at org.springdoc.webmvc.api.OpenApiWebMvcResource.openapiJson(OpenApiWebMvcResource.java:117)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:258)
	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:191)
	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:118)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:986)
	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:891)
	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1089)
	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:979)
	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014)
	at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:903)
	at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:564)
	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885)
	at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:195)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at org.springframework.web.servlet.resource.ResourceUrlEncodingFilter.doFilter(ResourceUrlEncodingFilter.java:66)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at io.sentry.spring.jakarta.SentryUserFilter.doFilterInternal(SentryUserFilter.java:56)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:108)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:108)
	at org.springframework.security.web.ObservationFilterChainDecorator$FilterObservation$SimpleFilterObservation.lambda$wrap$1(ObservationFilterChainDecorator.java:479)
	at org.springframework.security.web.ObservationFilterChainDecorator.lambda$wrapUnsecured$1(ObservationFilterChainDecorator.java:90)
	at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:219)
	at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:191)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:113)
	at org.springframework.web.filter.ServletRequestPathFilter.doFilter(ServletRequestPathFilter.java:52)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:113)
	at org.springframework.web.filter.CompositeFilter.doFilter(CompositeFilter.java:74)
	at org.springframework.security.config.annotation.web.configuration.WebSecurityConfiguration$CompositeFilterChainProxy.doFilter(WebSecurityConfiguration.java:319)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:113)
	at org.springframework.web.servlet.handler.HandlerMappingIntrospector.lambda$createCacheFilter$3(HandlerMappingIntrospector.java:243)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:113)
	at org.springframework.web.filter.CompositeFilter.doFilter(CompositeFilter.java:74)
	at org.springframework.security.config.annotation.web.configuration.WebMvcSecurityConfiguration$CompositeFilterChainProxy.doFilter(WebMvcSecurityConfiguration.java:240)
	at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:362)
	at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:278)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at org.springframework.web.filter.ServerHttpObservationFilter.doFilterInternal(ServerHttpObservationFilter.java:114)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at io.sentry.spring.jakarta.tracing.SentryTracingFilter.doFilterInternal(SentryTracingFilter.java:120)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at io.sentry.spring.jakarta.SentrySpringFilter.doFilterInternal(SentrySpringFilter.java:79)
	at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:483)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:116)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:344)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:398)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:903)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1740)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1189)
	at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:658)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63)
	at java.base/java.lang.Thread.run(Thread.java:1583)

To Reproduce
Steps to reproduce the behavior:

• What version of spring-boot you are using? -> Spring Boot 3.5
• What modules and versions of springdoc-openapi are you using? -> org.springdoc:springdoc-openapi-starter-webmvc-ui version 2.8.9

Expected behavior

• No NullPointerException should be thrown

Additional context

• Java 21 Upgrade Frachtwerk/essencium-backend#711
• The problem seems to be that in the SchemaUtils in line 261, the statement String specVersion = schema.getSpecVersion().name(); accesses a schema object that is read as null in the AbstractRequestService in line 619.
• If I bluntly remove all @NotNull annotations, no exception is thrown and a valid openAPI document is generated.