Migrate from FirebaseInstanceId.getInstance().getId() to FirebaseInstallations.getInstance().getId()

I have to migrate from the deprecated synchronous api FirebaseInstanceId.getInstance().getId(); to the new async firebase api:

FirebaseInstallations.getInstance().getId().addOnCompleteListener( task -> {
                                if (!task.isSuccessful()) {
                                    Log.w(TAG, "getInstanceId failed", task.getException());
                                    return;
                                }
                                // Get new Instance ID 
                                String id = task.getResult();
                            });

My problem is that in my old project, in many different point of my code a method like the following one has being called, and all the called expecting a response synchrounus in-line without callback:

public static String getDeviceId() {
    if (deviceId == null) {
        initDeviceId();
    }
    return deviceId;
}

private static void initDeviceId() {
    deviceId = FirebaseInstanceId.getInstance().getId();
}

How can migrate the code without rewriting all the project ? I have thought to to edit the above methods in this way:

public static String getDeviceId() {
    if (deviceId == null) {
        deviceId = workerThread.submit(initDeviceId()).get()
    }
    return deviceId;
}

private fun initDeviceId():Callable<String?>{
    return Callable {
        val latch = CountDownLatch(1)
        var result:String ?= null
        FirebaseInstallations.getInstance().id.addOnCompleteListener{ 
            task -> result = task.result
                    latch.countDown()
        }
        
        latch.await()
        result
    }
}

but in this way I risk to block mainthread.