Cannot add extension with name 'googleServices', as there is an extension already registered with that name

Please help me. Problems connecting firebase with firebase Assistant in android studio.

I'm trying to connect firebase analytics with ionic, and for that I have to connect with firebase. I followed the steps by the wizard but it is giving this error:

The library com.google.android.gms:play-services-base is being requested by various other libraries at [[11.0.1,11.0.1]], but resolves to 15.0.1. Disable the plugin and check your dependencies tree using ./gradlew :app:dependencies.

Project.properties:

    target=android-27
android.library.reference.1=CordovaLib
android.library.reference.2=app
# cordova.system.library.1=com.google.android.gms:play-services-analytics:11.0.1
cordova.gradle.include.1=cordova-support-google-services/android-build.gradle
cordova.system.library.2=com.google.firebase:firebase-core:16.0.+
cordova.gradle.include.2=cordova-android-play-services-gradle-release/br-cordova-android-play-services-gradle-release.gradle
cordova.gradle.include.3=cordova-android-firebase-gradle-release/br-cordova-android-firebase-gradle-release.gradle

Projectc/build.gradle:

      buildscript {
    repositories {
        maven {
            url "https://maven.google.com"
        }
        jcenter()
    }
    dependencies {

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
        classpath 'com.android.tools.build:gradle:3.0.1'
      classpath 'com.google.gms:google-services:4.1.0'
    }
}

allprojects {
    repositories {
        maven {
            url "https://maven.google.com"
        }
        jcenter()
    }
    //This replaces project.properties w.r.t. build settings
    project.ext {
      defaultBuildToolsVersion="27.0.1" //String
      defaultMinSdkVersion=19 //Integer - Minimum requirement is Android 4.4
      defaultTargetSdkVersion=27 //Integer - We ALWAYS target the latest by default
      defaultCompileSdkVersion=27 //Integer - We ALWAYS compile with the latest by default
    }
}

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

App/build.gradle:

    apply plugin: 'com.android.application'

buildscript {
    repositories {
        mavenCentral()
        maven {
            url "https://maven.google.com"
        }
        jcenter()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
    }
}

// Allow plugins to declare Maven dependencies via build-extras.gradle.
allprojects {
    repositories {
        mavenCentral();
        jcenter()
    }
}

task wrapper(type: Wrapper) {
    gradleVersion = '4.1.0'
}

// Configuration properties. Set these via environment variables, build-extras.gradle, or gradle.properties.
// Refer to: http://www.gradle.org/docs/current/userguide/tutorial_this_and_that.html
ext {
    apply from: '../CordovaLib/cordova.gradle'
    // The value for android.compileSdkVersion.
    if (!project.hasProperty('cdvCompileSdkVersion')) {
        cdvCompileSdkVersion = null;
    }
    // The value for android.buildToolsVersion.
    if (!project.hasProperty('cdvBuildToolsVersion')) {
        cdvBuildToolsVersion = null;
    }
    // Sets the versionCode to the given value.
    if (!project.hasProperty('cdvVersionCode')) {
        cdvVersionCode = null
    }
    // Sets the minSdkVersion to the given value.
    if (!project.hasProperty('cdvMinSdkVersion')) {
        cdvMinSdkVersion = null
    }
    // Whether to build architecture-specific APKs.
    if (!project.hasProperty('cdvBuildMultipleApks')) {
        cdvBuildMultipleApks = null
    }
    // Whether to append a 0 "abi digit" to versionCode when only a single APK is build
    if (!project.hasProperty('cdvVersionCodeForceAbiDigit')) {
        cdvVersionCodeForceAbiDigit = null
    }
    // .properties files to use for release signing.
    if (!project.hasProperty('cdvReleaseSigningPropertiesFile')) {
        cdvReleaseSigningPropertiesFile = null
    }
    // .properties files to use for debug signing.
    if (!project.hasProperty('cdvDebugSigningPropertiesFile')) {
        cdvDebugSigningPropertiesFile = null
    }
    // Set by build.js script.
    if (!project.hasProperty('cdvBuildArch')) {
        cdvBuildArch = null
    }

    // Plugin gradle extensions can append to this to have code run at the end.
    cdvPluginPostBuildExtras = []
}

// PLUGIN GRADLE EXTENSIONS START
apply from: "../cordova-support-google-services/android-build.gradle"
apply from: "../cordova-android-play-services-gradle-release/br-cordova-android-play-services-gradle-release.gradle"
apply from: "../cordova-android-firebase-gradle-release/br-cordova-android-firebase-gradle-release.gradle"
apply plugin: 'com.google.gms.google-services'
// PLUGIN GRADLE EXTENSIONS END

def hasBuildExtras1 = file('build-extras.gradle').exists()
if (hasBuildExtras1) {
    apply from: 'build-extras.gradle'
}

def hasBuildExtras2 = file('../build-extras.gradle').exists()
if (hasBuildExtras2) {
    apply from: '../build-extras.gradle'
}

// Set property defaults after extension .gradle files.
if (ext.cdvCompileSdkVersion == null) {
    ext.cdvCompileSdkVersion = privateHelpers.getProjectTarget()
    //ext.cdvCompileSdkVersion = project.ext.defaultCompileSdkVersion
}
if (ext.cdvBuildToolsVersion == null) {
    ext.cdvBuildToolsVersion = privateHelpers.findLatestInstalledBuildTools()
    //ext.cdvBuildToolsVersion = project.ext.defaultBuildToolsVersion
}
if (ext.cdvDebugSigningPropertiesFile == null && file('../debug-signing.properties').exists()) {
    ext.cdvDebugSigningPropertiesFile = '../debug-signing.properties'
}
if (ext.cdvReleaseSigningPropertiesFile == null && file('../release-signing.properties').exists()) {
    ext.cdvReleaseSigningPropertiesFile = '../release-signing.properties'
}

// Cast to appropriate types.
ext.cdvBuildMultipleApks = cdvBuildMultipleApks == null ? false : cdvBuildMultipleApks.toBoolean();
ext.cdvVersionCodeForceAbiDigit = cdvVersionCodeForceAbiDigit == null ? false : cdvVersionCodeForceAbiDigit.toBoolean();
ext.cdvMinSdkVersion = cdvMinSdkVersion == null ? defaultMinSdkVersion : Integer.parseInt('' + cdvMinSdkVersion)
ext.cdvVersionCode = cdvVersionCode == null ? null : Integer.parseInt('' + cdvVersionCode)

def computeBuildTargetName(debugBuild) {
    def ret = 'assemble'
    if (cdvBuildMultipleApks && cdvBuildArch) {
        def arch = cdvBuildArch == 'arm' ? 'armv7' : cdvBuildArch
        ret += '' + arch.toUpperCase().charAt(0) + arch.substring(1);
    }
    return ret + (debugBuild ? 'Debug' : 'Release')
}

// Make cdvBuild a task that depends on the debug/arch-sepecific task.
task cdvBuildDebug
cdvBuildDebug.dependsOn {
    return computeBuildTargetName(true)
}

task cdvBuildRelease
cdvBuildRelease.dependsOn {
    return computeBuildTargetName(false)
}

task cdvPrintProps << {
    println('cdvCompileSdkVersion=' + cdvCompileSdkVersion)
    println('cdvBuildToolsVersion=' + cdvBuildToolsVersion)
    println('cdvVersionCode=' + cdvVersionCode)
    println('cdvVersionCodeForceAbiDigit=' + cdvVersionCodeForceAbiDigit)
    println('cdvMinSdkVersion=' + cdvMinSdkVersion)
    println('cdvBuildMultipleApks=' + cdvBuildMultipleApks)
    println('cdvReleaseSigningPropertiesFile=' + cdvReleaseSigningPropertiesFile)
    println('cdvDebugSigningPropertiesFile=' + cdvDebugSigningPropertiesFile)
    println('cdvBuildArch=' + cdvBuildArch)
    println('computedVersionCode=' + android.defaultConfig.versionCode)
    android.productFlavors.each { flavor ->
        println('computed' + flavor.name.capitalize() + 'VersionCode=' + flavor.versionCode)
    }
}

android {

    defaultConfig {
        versionCode cdvVersionCode ?: new BigInteger("" + privateHelpers.extractIntFromManifest("versionCode"))
        applicationId privateHelpers.extractStringFromManifest("package")

        if (cdvMinSdkVersion != null) {
            minSdkVersion cdvMinSdkVersion
        }
    }

    lintOptions {
        abortOnError false;
    }

    compileSdkVersion cdvCompileSdkVersion
    buildToolsVersion cdvBuildToolsVersion

    // This code exists for Crosswalk and other Native APIs.
    // By default, we multiply the existing version code in the
    // Android Manifest by 10 and add a number for each architecture.
    // If you are not using Crosswalk or SQLite, you can
    // ignore this chunk of code, and your version codes will be respected.

    if (Boolean.valueOf(cdvBuildMultipleApks)) {
        flavorDimensions "default"

        productFlavors {
            armeabi {
                versionCode defaultConfig.versionCode * 10 + 1
                ndk {
                    abiFilters = ["armeabi"]
                }
            }
            armv7 {
                versionCode defaultConfig.versionCode * 10 + 2
                ndk {
                    abiFilters = ["armeabi-v7a"]
                }
            }
            arm64 {
                versionCode defaultConfig.versionCode * 10 + 3
                ndk {
                    abiFilters = ["arm64-v8a"]
                }
            }
            x86 {
                versionCode defaultConfig.versionCode * 10 + 4
                ndk {
                    abiFilters = ["x86"]
                }
            }
            x86_64 {
                versionCode defaultConfig.versionCode * 10 + 5
                ndk {
                    abiFilters = ["x86_64"]
                }
            }
        }
    } else if (Boolean.valueOf(cdvVersionCodeForceAbiDigit)) {
        // This provides compatibility to the default logic for versionCode before cordova-android 5.2.0
        defaultConfig {
            versionCode defaultConfig.versionCode * 10
        }
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }

    if (cdvReleaseSigningPropertiesFile) {
        signingConfigs {
            release {
                // These must be set or Gradle will complain (even if they are overridden).
                keyAlias = ""
                keyPassword = "__unset"
                // And these must be set to non-empty in order to have the signing step added to the task graph.
                storeFile = null
                storePassword = "__unset"
            }
        }
        buildTypes {
            release {
                signingConfig signingConfigs.release
            }
        }
        addSigningProps(cdvReleaseSigningPropertiesFile, signingConfigs.release)
    }
    if (cdvDebugSigningPropertiesFile) {
        addSigningProps(cdvDebugSigningPropertiesFile, signingConfigs.debug)
    }
}

/*
 * WARNING: Cordova Lib and platform scripts do management inside of this code here,
 * if you are adding the dependencies manually, do so outside the comments, otherwise
 * the Cordova tools will overwrite them
 */


dependencies {
    implementation fileTree(dir: 'libs', include: '*.jar')
    // SUB-PROJECT DEPENDENCIES START
    implementation(project(path: ":CordovaLib"))
    implementation "com.google.firebase:firebase-core:16.0.+"
    // SUB-PROJECT DEPENDENCIES END
}

def promptForReleaseKeyPassword() {
    if (!cdvReleaseSigningPropertiesFile) {
        return;
    }
    if ('__unset'.equals(android.signingConfigs.release.storePassword)) {
        android.signingConfigs.release.storePassword = privateHelpers.promptForPassword('Enter key store password: ')
    }
    if ('__unset'.equals(android.signingConfigs.release.keyPassword)) {
        android.signingConfigs.release.keyPassword = privateHelpers.promptForPassword('Enter key password: ');
    }
}

gradle.taskGraph.whenReady { taskGraph ->
    taskGraph.getAllTasks().each() { task ->
        if (['validateReleaseSigning', 'validateSigningRelease', 'validateSigningArmv7Release', 'validateSigningX76Release'].contains(task.name)) {
            promptForReleaseKeyPassword()
        }
    }
}

def addSigningProps(propsFilePath, signingConfig) {
    def propsFile = file(propsFilePath)
    def props = new Properties()
    propsFile.withReader { reader ->
        props.load(reader)
    }

    def storeFile = new File(props.get('key.store') ?: privateHelpers.ensureValueExists(propsFilePath, props, 'storeFile'))
    if (!storeFile.isAbsolute()) {
        storeFile = RelativePath.parse(true, storeFile.toString()).getFile(propsFile.getParentFile())
    }
    if (!storeFile.exists()) {
        throw new FileNotFoundException('Keystore file does not exist: ' + storeFile.getAbsolutePath())
    }
    signingConfig.keyAlias = props.get('key.alias') ?: privateHelpers.ensureValueExists(propsFilePath, props, 'keyAlias')
    signingConfig.keyPassword = props.get('keyPassword', props.get('key.alias.password', signingConfig.keyPassword))
    signingConfig.storeFile = storeFile
    signingConfig.storePassword = props.get('storePassword', props.get('key.store.password', signingConfig.storePassword))
    def storeType = props.get('storeType', props.get('key.store.type', ''))
    if (!storeType) {
        def filename = storeFile.getName().toLowerCase();
        if (filename.endsWith('.p12') || filename.endsWith('.pfx')) {
            storeType = 'pkcs12'
        } else {
            storeType = signingConfig.storeType // "jks"
        }
    }
    signingConfig.storeType = storeType
}

for (def func : cdvPluginPostBuildExtras) {
    func()
}

// This can be defined within build-extras.gradle as:
//     ext.postBuildExtras = { ... code here ... }
if (hasProperty('postBuildExtras')) {
    postBuildExtras()
}