title: OneSignal causing Google Play Services version to change
body: <p>I'm trying to integrate OneSignal into my project, but it's causing errors with Google Play Services.</p>
  
  <p>This is my <code>build.gradle</code>:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  apply plugin: 'kotlin-android'
  apply plugin: 'kotlin-android-extensions'
  apply plugin: 'io.fabric'
  
  dependencies {
      ...
  
      implementation "com.google.firebase:firebase-core:16.0.1"
      implementation "com.google.firebase:firebase-messaging:17.3.0"
  
      implementation "com.google.android.gms:play-services-plus:15.0.1"
      implementation "com.google.android.gms:play-services-auth:15.0.1"
      implementation "com.google.android.gms:play-services-location:15.0.1"
      implementation "com.google.android.gms:play-services-maps:15.0.1"
      implementation "com.google.android.gms:play-services-places:15.0.1"
      implementation "com.google.android.gms:play-services-wallet:15.0.1"
  
      ...
  }
  
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>Now, I added OneSignal.</p>
  
  <pre><code>buildscript {
      ...
  
      dependencies {
          ...
  
          classpath 'gradle.plugin.com.onesignal:onesignal-gradle-plugin:0.8.1'
  
          ...
      }
  }
  </code></pre>
  
  <p>And here is my updated <code>build.gradle</code>:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  apply plugin: 'kotlin-android'
  apply plugin: 'kotlin-android-extensions'
  apply plugin: 'io.fabric'
  
  apply plugin: 'com.onesignal.androidsdk.onesignal-gradle-plugin'
  
  dependencies {
      ...
  
      implementation "com.google.firebase:firebase-core:16.0.1"
      implementation "com.google.firebase:firebase-messaging:17.3.0"
  
      implementation "com.google.android.gms:play-services-plus:15.0.1"
      implementation "com.google.android.gms:play-services-auth:15.0.1"
      implementation "com.google.android.gms:play-services-location:15.0.1"
      implementation "com.google.android.gms:play-services-maps:15.0.1"
      implementation "com.google.android.gms:play-services-places:15.0.1"
      implementation "com.google.android.gms:play-services-wallet:15.0.1"
  
      ...
  
      implementation 'com.onesignal:OneSignal:3.9.1'
  
      ...
  }
  
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>Now, syncing with this will cause errors:</p>
  
  <pre><code>Failed to resolve: com.google.firebase:firebase-core:17.3.0
  ...
  
  Failed to resolve: com.google.android.gms:play-services-plus:17.3.0
  ...
  
  Failed to resolve: com.google.android.gms:play-services-auth:17.3.0
  ...
  </code></pre>
  
  <p>For some reason adding OneSignal causes Google Play Services to be bumped up to to my <code>firebase-messaging</code> version ( 17.3.0 )</p>
  
  <p>Is there any way to fix this? Thanks.</p>