https://adtmag.com/articles/2020/01/27/javalin-framework-update.aspx

The latest release of Javalin, the lightweight Web framework for Kotlin and Java, is a minor, mostly bug-fix release, but the steady evolution and growing popularity of this open-source project are a kind of validation of this type minimalist framework.

A new version of Javalin has been released approximately twice a month (on average) since version 1.0 was released in November 2017. And all major releases have, so far, been backwards compatible.