Multiple of our CIs currently run with -PfailOnWarnings=true. This is observed by our main build.gradle to enable -Werror:

We should observe the property for Android as well. This will help keep our builds clean and prevent things like #6866.

Android also has a fair number of linter warnings. It would be nice if we got to a place where they were covered by -PfailOnWarnings=true as well, but that could happen later (in which case we should create a new issue to track it).