Custom firebase messaging service

MyFirebaseMessagingService.kt

package com.spreys.pushnotifications

import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import android.media.RingtoneManager
import android.os.Build
import androidx.core.app.NotificationCompat
import com.google.firebase.messaging.FirebaseMessagingService
import com.google.firebase.messaging.RemoteMessage

class MyFirebaseMessagingService: FirebaseMessagingService() {
    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        super.onMessageReceived(remoteMessage)

        remoteMessage.notification?.title?.let { title ->
            remoteMessage.notification?.body?.let { body ->
                sendNotification(title, body)
            }
        }
    }

    private fun sendNotification(title: String, body: String) {
        val intent = Intent(this, MainActivity::class.java)
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)

        val pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_ONE_SHOT)

        val channelId = "default"
        val defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION)

        val notificationBuilder = NotificationCompat.Builder(this, channelId)
            .setSmallIcon(R.mipmap.ic_launcher_round)
            .setContentTitle(title)
            .setContentText(body)
            .setAutoCancel(true)
            .setSound(defaultSoundUri)
            .setContentIntent(pendingIntent)

        val notificationManager = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val channel = NotificationChannel(channelId, "Channel title", NotificationManager.IMPORTANCE_DEFAULT)
            notificationManager.createNotificationChannel(channel)
        }

        notificationManager.notify(0, notificationBuilder.build())
    }
}