Databinding seems to be broken after adding Room

Turns out, javac will print a maximum of 100 compilation errors, and when dealing with preprocessors you often want the last error message, not the first. Put this in your top-level build.gradle file and become happy:

allprojects {
    gradle.projectsEvaluated {
        tasks.withType(JavaCompile) {
            options.compilerArgs << "-Xmaxerrs" << "4000"
            options.compilerArgs << "-Xmaxwarns" << "4000"
        }
    }
}

Thanks to: https://movieos.org/2017/android-room-data-binding-compile-time-errors/