Add ability to record reasons for the JVM version change #1742
Description
In start.spring.io, we change the JVM version when:
- The Spring Boot version doesn't support the Java version (e.g. using Spring Boot 3.x with Java 8)
- Kotlin doesn't support the JVM version yet (e.g. Kotlin 2.20 with Java 25)
The InvalidJvmVersionHelpDocumentCustomizer can handle those cases, although one could select Kotlin, Java 8 and Spring Boot 3 and the help file would state something wrong.
Additionally, we now have two dependencies which have a higher baseline than Spring Boot has: Vaadin and jOOQ both have Java 21 as a baseline.
When adding such a dependency, the help document is plain wrong.
It would be nice to have a way to record the reason why the JVM version has been changed so that this reason can be transferred into the help document.