Spring warns about not having jackson-module-kotlin

Question

Just upgraded OkHttp to 4.4.0 and came from 3.3.0. I understand OkHttp now relies on Kotlin, but this now gives some unwanted side-effects with Spring Boot (2.2.5) and Jackson as it now warns about not having the com.fasterxml.jackson.module:jackson-module-kotlin on the classpath.

Now I'm kind of forced to add this lib, because moving to 4.4.0 to prevent this warning. Is there a way to prevent this somehow? I guess not having kotlin on the classpath is not possible ;-)

Answer 1

OkHttp transitively pulls the kotlin stdlib into your classpath. This is detected by jackson which in turn emits the warning.

Unless you have some DTO classes written in Kotlin which should be (de-)serialized by jackson, you can ignore the warning.