After migrating to Spring Boot 2.5.0 I get the following warning during startup:
WARN | o.s.h.c.j.Jackson2ObjectMapperBuilder | For Jackson Kotlin classes support please add "com.fasterxml.jackson.module:jackson-module-kotlin" to the classpath
Another person posting this StackOverflow question has this issue as well, but there is no clear/easy solution for it without code changes.
Just like this person I am not using Kotlin at all. Please make it easy to exclude Kotlin from autoconfiguration (as for example like with ThymeLeaf with exclude = {ThymeleafAutoConfiguration.class}, or maybe even solve this automatically for the user entirely.
Comment From: snicoll
@bas83 thanks for the report but that warning is logged by Spring Framework based on the presence of a kotlin-specific jar. The SO question you've shared has a comment that links to https://github.com/spring-projects/spring-framework/issues/26962.
Can you please confirm your application uses Spring Security?
Comment From: Bas83
Yes I am using Spring Security. Should I report this to them instead? In your link I found this issue: https://github.com/spring-projects/spring-security/issues/9811
Comment From: snicoll
Thanks for confirming. Yes, that's the root cause of your issue. Please subscribe to that issue for further update. On our side, we'll add a temporary exclude as I am not sure that Spring Security 5.5.1 will be out before Spring Boot 2.5.1.