I add "android:configChanges: layoutDirection" to AndroidManifest, but after build, it is not exist!

I add "android:configChanges: layoutDirection" to AndroidManifest to resolve that when I change android system language, the app will resume. so I find a way to add android:configChanges: layoutDirection, but when I build new apk and test it , it is still not working! so I export the project, and see the AndroidManifest, but I can not find "layoutDirection". I try unity 5.3.4, and 5.4.3, but it still can not be added. Please who can tell me why.