title: Supertypes of the following classes cannot be resolved
body: <p>I have <code>android</code> <code>app</code> in <code>kotlin</code> which is giving me this error.</p>
  
  <blockquote>
    <p>Error: Supertypes of the following classes cannot be resolved. Please make sure you have the required dependencies in the classpath:
        class com.google.firebase.auth.FirebaseAuth, unresolved supertypes: com.google.android.gms.internal.aad</p>
  </blockquote>
  
  <p>and this </p>
  
  <blockquote>
    <p>Error:Execution failed for task ':app:compileDebugKotlin'.</p>
  </blockquote>
  
  <p>Compilation error. See log for more details</p>
  
  <p>this is my app module </p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  apply plugin: 'kotlin-android'
  
  apply plugin: 'kotlin-android-extensions'
  
  android {
      compileSdkVersion 26
      defaultConfig {
          applicationId "appname"
          minSdkVersion 15
          targetSdkVersion 26
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
  
       implementation 'com.android.support:appcompat-v7:26.1.0'
       implementation 'com.android.support:animated-vector-drawable:26.1.0'
      implementation 'com.android.support:mediarouter-v7:26.1.0'
     implementation 'com.android.support.constraint:constraint-layout:1.0.2'
      implementation 'com.android.support:appcompat-v7:26.1.0'
      implementation 'com.android.support:recyclerview-v7:26.1.0'
      implementation 'com.android.support:cardview-v7:26.1.0'
      implementation 'com.android.support:design:26.1.0'
  
      implementation 'com.firebaseui:firebase-ui-database:3.0.0'
  
  
  
      //noinspection GradleCompatible,GradleCompatible
      implementation 'com.google.android.gms:play-services:11.0.4'
      implementation 'com.google.firebase:firebase-auth:11.0.4'
      implementation 'com.google.firebase:firebase-database:11.0.4'
      implementation 'com.google.firebase:firebase-storage:11.0.4'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.1'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
      compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
  
  }
  
   repositories {
      mavenCentral()
  }
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>and my project gradle is this </p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  
  buildscript {
      ext.kotlin_version = '1.1.51'
      repositories {
          google()
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.0.1'
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
          classpath 'com.google.gms:google-services:3.1.0'
  
      }
  }
  
  allprojects {
      repositories {
          google()
          jcenter()
          maven { url "https://jitpack.io" }
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  
  <p>I have <code>firebase.auth implementation</code> but still, it's showing me the error. </p>