Firebase notification integration throws java.lang.IncompatibleClassChangeError
<p>I'm trying to integrate firebase notification to existing android application. But when the app start it crashes.</p>

<pre><code>Process: uk.co.stableweb.geethika, PID: 24344
  java.lang.IncompatibleClassChangeError: com.google.firebase.auth.FirebaseAuth
      at dalvik.system.DexFile.defineClassNative(Native Method)
      at dalvik.system.DexFile.defineClass(DexFile.java:226)
      at dalvik.system.DexFile.loadClassBinaryName(DexFile.java:219)
      at dalvik.system.DexPathList.findClass(DexPathList.java:338)
      at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:54)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:511)
      at java.lang.ClassLoader.loadClass(ClassLoader.java:469)
      at java.lang.Class.classForName(Native Method)
      at java.lang.Class.forName(Class.java:324)
      at java.lang.Class.forName(Class.java:285)
      at com.google.firebase.FirebaseApp.zza(Unknown Source)
      at com.google.firebase.FirebaseApp.initializeApp(Unknown Source)
      at com.google.firebase.FirebaseApp.initializeApp(Unknown Source)
      at com.google.firebase.FirebaseApp.zzeh(Unknown Source)
      at com.google.firebase.provider.FirebaseInitProvider.onCreate(Unknown Source)
      at android.content.ContentProvider.attachInfo(ContentProvider.java:1748)
      at android.content.ContentProvider.attachInfo(ContentProvider.java:1723)
      at com.google.firebase.provider.FirebaseInitProvider.attachInfo(Unknown Source)
      at android.app.ActivityThread.installProvider(ActivityThread.java:5233)
      at android.app.ActivityThread.installContentProviders(ActivityThread.java:4828)
      at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4768)
      at android.app.ActivityThread.access$1600(ActivityThread.java:154)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1441)
      at android.os.Handler.dispatchMessage(Handler.java:102)
      at android.os.Looper.loop(Looper.java:152)
      at android.app.ActivityThread.main(ActivityThread.java:5497)
      at java.lang.reflect.Method.invoke(Native Method)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
07-18 10:47:24.284 24344-24344/uk.co.stableweb.geethika D/AppTracker: App Event: crash
</code></pre>

<p>This is app.grade.</p>

<pre><code>compile 'com.android.support:appcompat-v7:23.4.0'
    compile 'com.android.support:design:23.4.0'
    compile 'com.android.support.constraint:constraint-layout:1.0.0-alpha4'
    compile 'com.google.firebase:firebase-core:9.2.0'
    compile 'com.google.firebase:firebase-database:9.2.0'
    compile 'com.android.support:cardview-v7:23.4.0'
    compile 'com.android.support:recyclerview-v7:23.4.0'
    compile 'com.firebaseui:firebase-ui:0.4.1'
    compile 'com.firebaseui:firebase-ui-database:0.4.1'
    compile 'com.firebaseui:firebase-ui-auth:0.4.1'
    compile 'org.sufficientlysecure:html-textview:1.6'
    compile 'com.android.support:support-v4:23.4.0'
    compile 'cn.pedant.sweetalert:library:1.3'
    compile 'com.google.firebase:firebase-messaging:9.2.1'
</code></pre>

<p>In another question in stackoverflow, someone suggested to enable authentication. Even though I don't use authentication, I enabled anonymous option.</p>

<p><a href="https://i.stack.imgur.com/SQetE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/SQetE.png" alt="Firebase console"></a></p>

<p>And I updated google repository and play services in both device and SDK. If you have any idea on how to solve this it would be great. Thank you!</p>