MP OpenAPI 4.0 NPE during validation

[Azquelt]

Describe the bug

During validation, it's possible to get an NPE. The following stack was seen:

------Start of DE processing------ = [11/26/24, 23:32:59:989 PST ]
Exception = java.lang.NullPointerException
Source = io.openliberty.microprofile.openapi20.internal.ApplicationProcessor
probeid = 291
Stack Dump = java.lang.NullPointerException: Cannot invoke "java.lang.String.contains(java.lang.CharSequence)" because "key" is null
	at io.openliberty.microprofile.openapi40.internal.services.validation.PathItem31Validator.validate(PathItem31Validator.java:44)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31Validator$ValidationOperation31.visitPathItem(OpenAPI31Validator.java:74)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.traversePathItem(OpenAPIModelWalkerImpl.java:399)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31ModelWalkerImpl$Walker31.traverseModelObject(OpenAPI31ModelWalkerImpl.java:166)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31ModelWalkerImpl$Walker31.traverseObject(OpenAPI31ModelWalkerImpl.java:120)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31ModelWalkerImpl$Walker31.lambda$traverseSchemaChildren$1(OpenAPI31ModelWalkerImpl.java:109)
	at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:986)
	at java.base/java.util.Collections$UnmodifiableMap.forEach(Collections.java:1707)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31ModelWalkerImpl$Walker31.traverseSchemaChildren(OpenAPI31ModelWalkerImpl.java:107)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.traverseSchema(OpenAPIModelWalkerImpl.java:930)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.lambda$processSchemas$20(OpenAPIModelWalkerImpl.java:1751)
	at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:986)
	at java.base/java.util.Collections$UnmodifiableMap.forEach(Collections.java:1707)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.processSchemas(OpenAPIModelWalkerImpl.java:1749)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.traverseComponentChildren(OpenAPIModelWalkerImpl.java:340)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31ModelWalkerImpl$Walker31.traverseComponentChildren(OpenAPI31ModelWalkerImpl.java:95)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.traverseComponents(OpenAPIModelWalkerImpl.java:288)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.traverseOpenAPIChildren(OpenAPIModelWalkerImpl.java:218)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31ModelWalkerImpl$Walker31.traverseOpenAPIChildren(OpenAPI31ModelWalkerImpl.java:68)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.traverseOpenAPI(OpenAPIModelWalkerImpl.java:206)
	at io.openliberty.microprofile.openapi20.internal.utils.OpenAPIModelWalkerImpl$Walker.traverseOpenAPI(OpenAPIModelWalkerImpl.java:191)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31ModelWalkerImpl.walk(OpenAPI31ModelWalkerImpl.java:57)
	at io.openliberty.microprofile.openapi20.internal.validation.OASValidator30Impl$ValidationOperation.run(OASValidator30Impl.java:91)
	at io.openliberty.microprofile.openapi40.internal.services.impl.OpenAPI31Validator.validate(OpenAPI31Validator.java:46)
	at io.openliberty.microprofile.openapi20.internal.ValidationComponent.validateModel(ValidationComponent.java:95)
	at io.openliberty.microprofile.openapi20.internal.ValidationComponent.validateAndReportErrors(ValidationComponent.java:69)
	at io.openliberty.microprofile.openapi20.internal.ApplicationProcessor.processWebModule(ApplicationProcessor.java:290)
	at io.openliberty.microprofile.openapi20.internal.ApplicationProcessor.processApplication(ApplicationProcessor.java:145)
	at io.openliberty.microprofile.openapi20.internal.ApplicationRegistryImpl.addApplication(ApplicationRegistryImpl.java:113)
	at io.openliberty.microprofile.openapi20.internal.ApplicationListener.applicationStarting(ApplicationListener.java:48)
	at com.ibm.ws.container.service.state.internal.ApplicationStateManager.fireStarting(ApplicationStateManager.java:53)
	at com.ibm.ws.container.service.state.internal.StateChangeServiceImpl.fireApplicationStarting(StateChangeServiceImpl.java:52)
	at com.ibm.ws.app.manager.module.internal.SimpleDeployedAppInfoBase.preDeployApp(SimpleDeployedAppInfoBase.java:623)
	at com.ibm.ws.app.manager.module.internal.SimpleDeployedAppInfoBase.installApp(SimpleDeployedAppInfoBase.java:584)
	at com.ibm.ws.app.manager.module.internal.DeployedAppInfoBase.deployApp(DeployedAppInfoBase.java:625)
	at com.ibm.ws.app.manager.war.internal.WARApplicationHandlerImpl.install(WARApplicationHandlerImpl.java:67)
	at com.ibm.ws.app.manager.internal.statemachine.StartAction.execute(StartAction.java:199)
	at com.ibm.ws.app.manager.internal.statemachine.ApplicationStateMachineImpl.enterState(ApplicationStateMachineImpl.java:1369)
	at com.ibm.ws.app.manager.internal.statemachine.ApplicationStateMachineImpl.performAction(ApplicationStateMachineImpl.java:1213)
	at com.ibm.ws.app.manager.internal.statemachine.ApplicationStateMachineImpl.run(ApplicationStateMachineImpl.java:920)
	at com.ibm.ws.threading.internal.ExecutorServiceImpl$RunnableWrapper.run(ExecutorServiceImpl.java:298)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642)
	at java.base/java.lang.Thread.run(Thread.java:1595)

Steps to Reproduce

Seen while running the TCK in the MP70_EE10 configuration.

Not sure yet exactly which part of the TCK causes the NPE.

Expected behavior
We should not get an NPE here.

Diagnostic information:

• OpenLiberty Version: 24.0.0.12
• Affected feature(s): mpOpenAPI-4.0