Requirements

Spring Framework supports Kotlin 1.3+ and requires kotlin-stdlib (or one of its variants, such as kotlin-stdlib-jdk8) and kotlin-reflect to be present on the classpath. They are provided by default if you bootstrap a Kotlin project on start.spring.io.

Kotlin inline classes are not yet supported.
The Jackson Kotlin module is required for serializing or deserializing JSON data for Kotlin classes with Jackson, so make sure to add the com.fasterxml.jackson.module:jackson-module-kotlin dependency to your project if you have such need. It is automatically registered when found in the classpath.