Hi,
I use Undertow and after upgraded to v2.3.3, app failed to start with error NoClassDefFoundError;org.apache.commons.lang.ClassUtils in 'UndertowWebServerFactoryCustomizer' (see commit log https://github.com/spring-projects/spring-boot/commit/f0d90020e55a06cd9840040e2ec6709591a6e93a)
file https://github.com/spring-projects/spring-boot/commits/master/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/embedded/UndertowWebServerFactoryCustomizer.java
Thank you and best regards, Ionel.
Comment From: snicoll
Oops, thank you very much for the report. We meant to import ClassUtils from the core framework there.
Comment From: wilkinsona
This needs to be fixed in 2.2.x too. Thankfully we haven't released that one yet.
Comment From: snicoll
The import should have been prevented by a Checkstyle rule. Unfortunately it doesn't work as expected, I've created a separate issue to revisit it (#23062)