Actually there is no need to use flatMap

`null` values returned in the lambda are converted to empty `Optional`s in the `map` method: https://developer.android.com/reference/java/util/Optional#map(java.util.function.Function%3C?%20super%20T,%20?%20extends%20U%3E)

app/src/main/java/org/schabi/newpipe/fragments/detail/VideoDetailFragment.java

@@ -1887,7 +1887,7 @@ public final class VideoDetailFragment
         setupBrightness();
         if (!isPlayerAndPlayerServiceAvailable()
                 || player.UIs().get(MainPlayerUi.class).isEmpty()
-                || getRoot().flatMap(v -> Optional.ofNullable(v.getParent())).isEmpty()) {
+                || getRoot().map(View::getParent).isEmpty()) {
             return;
         }