Did you ever have android build failed issue because of dependency resolution?
… or you were curious where all these old rxjava dependencies come from?
You can pretty easy track the module causing issues via following gradle command.
gradlew :root-module:dependencyInsight \
--configuration debugRuntimeClasspath \ // or debugCompileClasspath
--dependency io.reactivex:rxjava:1.1.0 > dependencies.txt // saves result to 'dependencies.txt' file