We enabled -Werror for Java compilation in 2.4. It'd be nice to do the same for our Kotlin code as well. Ideally, we'd do it in 2.4.x to align with what we've done for Java but if it's too involved we could just do it in 2.5 instead.
Comment From: wilkinsona
We can't do this in 2.5 where we're using Kotlin 1.5. It generates a deprecation warning as we're compiling with language version and API version set to 1.3. It should be possible to suppress this with -Xsuppress-version-warnings but it doesn't work in 1.5.0-RC. The Kotlin team have said they'll fix that in 1.5.0 so we can tackle this once it has been released and we've upgraded.