All Parcelable CREATOR fields are @NonNull.

If they were null, then the Parcelable would fail to work.

Bug: 126726802
Test: manual
Change-Id: I7929ffa2f20e5de1c8e68e8263cca99496e9d014
Exempt-From-Owner-Approval: Trivial API annotations
diff --git a/api/removed.txt b/api/removed.txt
index 31dda47..fdfaf91 100644
--- a/api/removed.txt
+++ b/api/removed.txt
@@ -32,7 +32,7 @@
     method public int describeContents();
     method public void writeToParcel(android.os.Parcel, int);
     field public static final int CONTENTS_FILE_DESCRIPTOR = 1; // 0x1
-    field public static final android.os.Parcelable.Creator<android.app.PictureInPictureArgs> CREATOR;
+    field @NonNull public static final android.os.Parcelable.Creator<android.app.PictureInPictureArgs> CREATOR;
     field public static final int PARCELABLE_WRITE_RETURN_VALUE = 1; // 0x1
   }