Android Question FCM v1 - Unsubscribe from all topics

I tried the following code before posting here:

Try
jo = jo.InitializeStatic("com.google.firebase.iid.FirebaseInstallations").RunMethod("getInstance", Null)
jo.RunMethod("deleteInstanceId", Null)
Catch
Log("ERROR:" & LastException)
End Try

Click to expand...

but I get the error message:
Error occurred on line: 202 (Main)
java.lang.ClassNotFoundException: com.google$firebase$iid$FirebaseInstallations
at anywheresoftware.b4j.object.JavaObject.getCorrectClassName(JavaObject.java:289)
at anywheresoftware.b4j.object.JavaObject.InitializeStatic(JavaObject.java:75)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
at java.lang.reflect.Method.invoke(Native Method)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:157)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:201)
at anywheresoftware.b4a.shell.DebugResumableSub$RemoteResumableSub.resume(DebugResumableSub.java:22)
at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:275)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:150)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:201)
at anywheresoftware.b4a.keywords.Common$15.run(Common.java:1804)
at android.os.Handler.handleCallback(Handler.java:958)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loopOnce(Looper.java:230)
at android.os.Looper.loop(Looper.java:319)
at android.app.ActivityThread.main(ActivityThread.java:8919)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:578)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1103)

and

ERRORException) java.lang.Exception: java.lang.ClassNotFoundException: com.google$firebase$iid$FirebaseInstallations

You are probably looking for this class and method: https://firebase.google.com/docs/re.../installations/FirebaseInstallations#delete()
However, it looks like a mistake to use it for unsubscribing from all topics.

You should instead store the user topic. It can be done very easily with KeyValueStore.