title: Problems with cordova-plugin-firebase
body: <p>The build is failing after i added cordova-plugin-firebase. Every time i get a different error.
  I noticed that the plugin is changing my google-service.json as well.
  The most error i am getting is the following:</p>
  
  <pre><code> Execution failed for task ':app:fabricGenerateResourcesDebug'.
  &gt; Crashlytics Developer Tools error.
  app:fabricGenerateResourcesDebug FAILED
  ERROR - Crashlytics Developer Tools error.
  java.lang.IllegalArgumentException: Crashlytics found an invalid API key: 
  null.
  Check the Crashlytics plugin to make sure that the application has been 
  added successfully!
  Contact support@fabric.io for assistance.
  </code></pre>
  
  <p>I have no idea why is this tool needed and what has io fabric to do with it.
  I haven't installed or migrated anything from io fabric.
  here are my package.json dependencies: </p>
  
  <pre><code>"@angular/animations": "^8.1.2",
  "@angular/common": "^7.2.2",
  "@angular/core": "^7.2.2",
  "@angular/forms": "^7.2.2",
  "@angular/http": "^7.2.2",
  "@angular/platform-browser": "^7.2.2",
  "@angular/platform-browser-dynamic": "^7.2.2",
  "@angular/router": "^7.2.2",
  "@ionic-native/core": "^5.0.0",
  "@ionic-native/fabric": "^5.12.0",
  "@ionic-native/firebase": "^5.0.0",
  "@ionic-native/social-sharing": "^5.11.0",
  "@ionic-native/splash-screen": "^5.0.0",
  "@ionic-native/status-bar": "^5.0.0",
  "@ionic/angular": "^4.1.0",
  "@ionic/storage": "^2.2.0",
  "angularfire2": "^5.2.1",
  "cordova-android": "^8.0.0",
  "cordova-plugin-androidx": "^1.0.2",
  "cordova-plugin-androidx-adapter": "^1.1.0",
  "cordova-plugin-firebase": "^2.0.5",
  "cordova-plugin-x-socialsharing": "^5.4.7",
  "cordova-sqlite-storage": "^3.2.1",
  "cordova-support-google-services": "^1.3.1",
  "core-js": "^2.5.4",
  "es6-promise-plugin": "^4.2.2",
  "firebase": "^6.3.1",
  </code></pre>
  
  <p>*my app-level build gradle dependency:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  buildscript {
    repositories {
      mavenCentral()
      google()
      jcenter()
     }
  
    dependencies {
      classpath 'com.android.tools.build:gradle:3.3.0'
     }
   }
  
   dependencies {
   implementation fileTree(dir: 'libs', include: '*.jar')
  implementation 'com.google.firebase:firebase-core:17.0.0'
  // SUB-PROJECT DEPENDENCIES START
  implementation(project(path: ":CordovaLib"))
  implementation "com.google.android.gms:play-services-tagmanager:+"
  implementation "com.google.firebase:firebase-core:+"
  implementation "com.google.firebase:firebase-messaging:+"
  implementation "com.google.firebase:firebase-config:+"
  implementation "com.google.firebase:firebase-perf:+"
  implementation "androidx.annotation:annotation:1.0.0"
  implementation "androidx.legacy:legacy-support-v4:1.0.0"
  // SUB-PROJECT DEPENDENCIES END
  }
  </code></pre>
  
  <p>*my project level build-gradle dependencies:</p>
  
  <pre><code>   dependencies {
  
      // NOTE: Do not place your application dependencies here; they belong
      // in the individual module build.gradle files
      classpath 'com.android.tools.build:gradle:3.3.0'
  
      classpath 'com.google.gms:google-services:4.1.0' // google-services 
  dependency from cordova-plugin-firebase
  
      classpath 'io.fabric.tools:gradle:1.25.4' // fabric dependency from 
  cordova-plugin-firebase
      }
  </code></pre>
  
  <p>project properties:</p>
  
  <pre><code>target=android-28
  android.library.reference.1=CordovaLib
  android.library.reference.2=app
  cordova.gradle.include.1=cordova-android-firebase-gradle-release/promocat- 
  cordova-android-firebase-gradle-release.gradle
  cordova.gradle.include.2=cordova-plugin-firebase/promocat-build.gradle
  cordova.system.library.1=com.google.android.gms:play-services-tagmanager:+
  cordova.system.library.2=com.google.firebase:firebase-core:+
  cordova.system.library.3=com.google.firebase:firebase-messaging:+
  cordova.system.library.4=com.google.firebase:firebase-config:+
  cordova.system.library.5=com.google.firebase:firebase-perf:+
  cordova.system.library.6=androidx.annotation:annotation:1.0.0
  cordova.system.library.7=androidx.legacy:legacy-support-v4:1.0.0
  cordova.gradle.include.3=phonegap-plugin-multidex/promocat-multidex.gradle
  </code></pre>
  
  <p>after building, the plugin is changing my google-service.json that i downloaded from firebase to this:</p>
  
  <pre><code>"project_info": {
  "project_number": "123",
  "firebase_url": "https://cordova-plugin-firebase.firebaseio.com",
  "project_id": "cordova-plugin-firebase",
  "storage_bucket": "cordova-plugin-firebase.appspot.com"
   },
  "client": [
  {
    "client_info": {
      "mobilesdk_app_id": "1:123:android:123",
      "android_client_info": {
        "package_name": "com.github.cordova_plugin_firebase"
      }
    },
    "oauth_client": [
      {
        "client_id": "123.apps.googleusercontent.com",
        "client_type": 3
      }
    ],
    "api_key": [
      {
        "current_key": "123"
      }
    ],
    "services": {
      "analytics_service": {
        "status": 1
      },
      "appinvite_service": {
        "status": 1,
        "other_platform_oauth_client": []
      },
      "ads_service": {
        "status": 2
      }
    }
  }
  ],
  "configuration_version": "1"
   } 
  </code></pre>