How to fix Android compatibility warnings

Question

I have an app that is targeting Android 9 and I noticed in the Google Play prelaunch report a new section called Android compatibility. This new section lists warnings or errors related to the usage of unsupported APIs. The following is one of the problems and is listed as a greylisted API. Can someone explain which is the unsupported API in this case? The usage seems to be coming from the Android support library and not my code.

StrictMode policy violation: android.os.strictmode.NonSdkApiUsedViolation: Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V
    at android.os.StrictMode.lambda$static$1(StrictMode.java:428)
    at android.os.-$$Lambda$StrictMode$lu9ekkHJ2HMz0jd3F8K8MnhenxQ.accept(Unknown Source:2)
    at java.lang.Class.getDeclaredMethodInternal(Native Method)
    at java.lang.Class.getPublicMethodRecursive(Class.java:2075)
    at java.lang.Class.getMethod(Class.java:2063)
    at java.lang.Class.getMethod(Class.java:1690)
    at android.support.v7.widget.ViewUtils.makeOptionalFitsSystemWindows(ViewUtils.java:84)
    at android.support.v7.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:685)
    at android.support.v7.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:518)
    at android.support.v7.app.AppCompatDelegateImpl.onPostCreate(AppCompatDelegateImpl.java:299)
    at android.support.v7.app.AppCompatActivity.onPostCreate(AppCompatActivity.java:98)
    at android.app.Instrumentation.callActivityOnPostCreate(Instrumentation.java:1342)
    at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3002)
    at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:180)
    at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:165)
    at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:142)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:70)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1816)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6718)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Answer 1

I suppose there nothing we can do right now, just to wait that they fixed these issues in AndroidX (as Support Library won't be updated anymore).
As mentioned here the methods use reflection, so why the warning.