NoClassDefFoundError javax/servlet/ServletException with version 1.5.12

Describe the bug

• We have a Spring-Boot (Version 2.5.5) Web-Flux application that uses springdoc-openapi-webflux-ui. I don’t think we have any special configuration. Only relying on Spring-Boot’s autoconfiguration capabilities and using the Swagger annotations in a @RestController. When starting the application we receive the following exception since upgrading to 1.5.12:

Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springdoc.core.GenericResponseService]: Factory method 'responseBuilder' threw exception; nested exception is java.lang.NoClassDefFoundError: javax/servlet/ServletException
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.3.10.jar:5.3.10]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ~[spring-beans-5.3.10.jar:5.3.10]
	... 33 common frames omitted
Caused by: java.lang.NoClassDefFoundError: javax/servlet/ServletException
	at java.base/java.lang.ClassLoader.defineClass1(Native Method) ~[na:na]
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016) ~[na:na]
	at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:801) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:699) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:622) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580) ~[na:na]
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) ~[na:na]
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521) ~[na:na]
	at java.base/java.lang.ClassLoader.defineClass1(Native Method) ~[na:na]
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016) ~[na:na]
	at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:801) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:699) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:622) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580) ~[na:na]
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) ~[na:na]
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521) ~[na:na]
	at java.base/java.lang.ClassLoader.defineClass1(Native Method) ~[na:na]
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016) ~[na:na]
	at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:801) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:699) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:622) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580) ~[na:na]
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) ~[na:na]
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521) ~[na:na]
	at java.base/java.lang.ClassLoader.defineClass1(Native Method) ~[na:na]
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016) ~[na:na]
	at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:801) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:699) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:622) ~[na:na]
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:580) ~[na:na]
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) ~[na:na]
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521) ~[na:na]
	at java.base/java.lang.Class.forName0(Native Method) ~[na:na]
	at java.base/java.lang.Class.forName(Class.java:315) ~[na:na]
	at org.springdoc.core.GenericResponseService.<clinit>(GenericResponseService.java:115) ~[springdoc-openapi-common-1.5.12.jar:1.5.12]
	at org.springdoc.webflux.core.SpringDocWebFluxConfiguration.responseBuilder(SpringDocWebFluxConfiguration.java:138) ~[springdoc-openapi-webflux-core-1.5.12.jar:1.5.12]

Coming from version 1.5.11, the failing behavior seems to come from the exact changes that have been made in GenericResponseService: https://github.com/springdoc/springdoc-openapi/compare/v1.5.11...v1.5.12

It seems like the code can deal with a ClassNotFoundException but not a NoClassDefFoundError. Now I’m not sure whether this is a quirk of my application or actually a bug in springdoc-openapi

[hisener]

Yeah, that’s why my first suggestion is catching and throwing another exception to give a hint. That said, I am also okay with leaving as-is.

[skuzzle]

Meanwhile I also found out that we had a bogus dependency configuration pulling in spring-webmvc and I fixed the problem for us by fixing the dependencies.