Revert AndroidX fragment to version 1.6.2 (again)

java.lang.IndexOutOfBoundsException: Index -1 out of bounds for length 0
    at jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
    at jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
    at jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
    at java.util.Objects.checkIndex(Objects.java:359)
    at java.util.ArrayList.get(ArrayList.java:434)
    at androidx.fragment.app.FragmentManager.prepareBackStackState(SourceFile:9)
    at androidx.fragment.app.FragmentManager$PrepareBackStackTransitionState.generateOps(SourceFile:3)
    at androidx.fragment.app.FragmentManager.generateOpsForPendingActions(SourceFile:34)
    at androidx.fragment.app.FragmentManager.execPendingActions(SourceFile:9)
    at androidx.fragment.app.FragmentManager$5.run(SourceFile:4)
    at android.os.Handler.handleCallback(Handler.java:959)

app/build.gradle

@@ -549,7 +549,7 @@ dependencies {
     def emoji_version = "1.4.0" // 1.5.0-alpha01
     def flatbuffers_version = "2.0.0"
     def activity_version = " 1.9.0"
-    def fragment_version = "1.7.1" // 1.7.1 // 1.8.0-beta01
+    def fragment_version = "1.6.2" // 1.7.1 // 1.8.0-beta01
     def windows_version = "1.2.0" // 1.3.0-rc01
     def webkit_version = "1.10.0" // 1.11.0
     def recyclerview_version = "1.3.2" // 1.4.0-alpha01

app/src/main/java/eu/faircode/email/ApplicationEx.java

@@ -257,7 +257,7 @@ public class ApplicationEx extends Application
 
         // https://issuetracker.google.com/issues/341313071
         // https://developer.android.com/guide/navigation/custom-back/predictive-back-gesture#opt-predictive
-        FragmentManager.enablePredictiveBack(false);
+        //FragmentManager.enablePredictiveBack(false);
 
         if (Helper.hasWebView(this))
             CookieManager.getInstance().setAcceptCookie(false);