Unresolved reference: FirebaseMessagingService even after adding firebase-messaging dependency in Flutter Android module

I have an app that I want to add Firebase Cloud Messaging. Now, when configuring the services, I am getting this error in my Kotlin file:

Cannot resolve symbol 'FirebaseMessagingService'

When I try to add dependency on com.google.firbase:firebase-messaging and import, the dependency is being added into the project level and that is giving an error. Mind the dependency has already been downloaded in the app level, but its not being recognised by the Kotlin code.

I'm integrating Firebase Cloud Messaging into my Flutter project (Android part) and trying to extend FirebaseMessagingService in Kotlin.

However, I keep getting this error:

Unresolved reference: FirebaseMessagingService

Here’s my service class:

package com.swiftdrop.app;

import com.google.firebase.messaging.FirebaseMessagingService;

class NotificationService:FirebaseMessagingService() {
}

Here is my app level gradle:

plugins {
    id("com.android.application")
    id("com.google.gms.google-services")
    id("org.jetbrains.kotlin.android")
    id("dev.flutter.flutter-gradle-plugin")
}

android {
    namespace = "com.swiftdrop.app"
    compileSdk = 36
    ndkVersion = "27.2.12479018"

    compileOptions {
        sourceCompatibility = JavaVersion.VERSION_17
        targetCompatibility = JavaVersion.VERSION_17
        isCoreLibraryDesugaringEnabled = true
    }

    kotlinOptions {
        jvmTarget = "17"
    }

    defaultConfig {
        applicationId = "com.swiftdrop.app"
        minSdk = 23
        targetSdk = 36
        versionCode = flutter.versionCode
        versionName = flutter.versionName
        multiDexEnabled = true
    }

    buildTypes {
        release {
            signingConfig = signingConfigs.getByName("debug")
        }
    }

    buildFeatures {
        viewBinding = true
    }
}

dependencies {
    coreLibraryDesugaring("com.android.tools:desugar_jdk_libs:2.1.5")

    implementation(platform("com.google.firebase:firebase-bom:34.5.0"))
    implementation("com.google.firebase:firebase-messaging-ktx")
    implementation("com.google.firebase:firebase-appcheck-playintegrity")
    implementation("com.google.firebase:firebase-appcheck-debug")
    implementation("com.google.android.gms:play-services-recaptcha:17.1.0")

    implementation("com.squareup.retrofit2:retrofit:2.11.0")
    implementation("com.squareup.retrofit2:converter-moshi:2.11.0")
    implementation(kotlin("stdlib"))
}

flutter {
    source = "../.."
}

project level

// android/build.gradle.kts

plugins {
    id("com.android.application") version "8.11.0" apply false
    id("com.android.library") version "8.11.2" apply false
    id("org.jetbrains.kotlin.android") version "1.9.23" apply false
    id("com.google.gms.google-services") version "4.4.4" apply false
}

allprojects {
    repositories {
        google()
        mavenCentral()
    }
}

val newBuildDir: Directory = rootProject.layout.buildDirectory.dir("../../build").get()
rootProject.layout.buildDirectory.value(newBuildDir)

subprojects {
    val newSubprojectBuildDir: Directory = newBuildDir.dir(project.name)
    project.layout.buildDirectory.value(newSubprojectBuildDir)
    project.evaluationDependsOn(":app")
}

tasks.register<Delete>("clean") {
    delete(rootProject.layout.buildDirectory)
}