Dart Flutter sequential firebase_auth errors

Question

My aim is to make login system with e-mail and password with Firebase Auth. For this I installed the firebase_auth package and set all Firebase settings.

When I run the firebase_auth installed project, I get many errors like this:

The plugin `firebase_auth` uses a deprecated version of the Android embedding.
To avoid unexpected runtime failures, or future build failures, try to see if this plugin supports the Android V2 embedding. Otherwise, consider removing it since a future release of Flutter will remove these deprecated APIs.
If you are plugin author, take a look at the docs for migrating the plugin to the V2 embedding: https://flutter.dev/go/android-plugin-migration.
Launching lib\main.dart on Android SDK built for x86 in debug mode...
C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:8: error: package android.support.annotation does not exist
import android.support.annotation.NonNull;
                                 ^
C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:538: error: cannot find symbol

    public void onComplete(@NonNull Task<AuthResult> task) {
                            ^
  symbol:   class NonNull
  location: class FirebaseAuthPlugin.SignInCompleteListener
C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:558: error: cannot find symbol
    public void onComplete(@NonNull Task<Void> task) {

                            ^
  symbol:   class NonNull
  location: class FirebaseAuthPlugin.TaskVoidCompleteListener
C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:576: error: cannot find symbol
    public void onComplete(@NonNull Task<ProviderQueryResult> task) {
                            ^

  symbol:   class NonNull
  location: class FirebaseAuthPlugin.ProvidersCompleteListener
C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:175: error: cannot find symbol

                      public void onComplete(@NonNull Task<AuthResult> task) {
                                              ^
  symbol: class NonNull
C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:270: error: cannot find symbol
          public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                                          ^
  symbol: class NonNull
C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:435: error: cannot find symbol
              public void onComplete(@NonNull Task<GetTokenResult> task) {

                                      ^
  symbol: class NonNull
C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java:487: error: cannot find symbol
          public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                                          ^
  symbol: class NonNull
Note: C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\firebase_auth-0.6.2+1\android\src\main\java\io\flutter\plugins\firebaseauth\FirebaseAuthPlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
8 errors

FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':firebase_auth:compileDebugJavaWithJavac'.
> Compilation failed; see the compiler error output for details.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
* Get more help at https://help.gradle.org

BU�LD FAILED in 20s
Exception: Gradle task assembleDebug failed with exit code 1
Exited (sigterm)

---

pubspec.yaml:

name: simto_todolist
description: A new Flutter project.
publish_to: 'none'
version: 1.0.0+1

module:
  androidX: true

environment:
  sdk: '>=2.7.0 <3.0.0'

dependencies:
  flutter:
    sdk: flutter
  cupertino_icons: ^1.0.2

dev_dependencies:
  flutter_test:
    sdk: flutter
  global_configuration: ^1.6.0
  flutter_lints: ^1.0.0
  get_storage: ^2.0.3
  carousel_slider: ^4.0.0
  cool_alert: ^1.1.0
  timer_count_down: ^2.2.1
  modal_bottom_sheet: ^2.0.1
  persistent_bottom_nav_bar: ^4.0.2
  group_button: ^4.6.0
  flutter_signin_button: ^2.0.0
  google_sign_in: ^5.2.4
  firebase_core: ^1.13.1
  firebase_auth: ^0.6.2+1

flutter:
  uses-material-design: true
  assets:
  - splash1.png
  - splash2.png
  - splash3.png
  - splash4.png
  - logo.png
  
  fonts:
  - family: Roboto
    fonts:
    - asset: fonts/Roboto-Bold.ttf
    - asset: fonts/Roboto-Light.ttf
    - asset: fonts/Roboto-Medium.ttf
    - asset: fonts/Roboto-Thin.ttf

android/build.gradle:

buildscript {
    ext.kotlin_version = '1.6.10'
    repositories {
        google()
        mavenCentral()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:4.1.0'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 'com.google.gms:google-services:4.3.10'
    }
}

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

rootProject.buildDir = '../build'
subprojects {
    project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
    project.evaluationDependsOn(':app')
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

android/app/build.gradle:

def localProperties = new Properties()
def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'com.google.gms.google-services'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion flutter.compileSdkVersion

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    kotlinOptions {
        jvmTarget = '1.8'
    }

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        applicationId "io.simto.todolist.app"
        minSdkVersion 23
        targetSdkVersion flutter.targetSdkVersion
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    buildTypes {
        release {
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation 'com.google.firebase:firebase-analytics-ktx'
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation 'com.google.firebase:firebase-analytics-ktx'
}

I've been dealing with this error for almost a full day today and I'm about to go crazy. How can I fix these overlapping errors? Thank you very much in advance for the help.