title: "Error: Supertypes of the following classes cannot be resolved. Please make sure you have the required dependencies in the classpath"
body: <p>My Android project (Kotlin) doesn't compile.</p>
  
  <p><strong>Gradle log:</strong></p>
  
  <p><em>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.zzeku.</em> </p>
  
  <p><strong>Here's my app Gradle:</strong></p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  apply plugin: 'kotlin-android'
  
  apply plugin: 'kotlin-android-extensions'
  
  android {
      compileSdkVersion 27
      defaultConfig {
          applicationId "com.example.arturpoplawski.bandmanager"
          minSdkVersion 24
          targetSdkVersion 27
          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'])
  
      //kotlin
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
      implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
      implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
  
      //android
      implementation 'com.android.support:appcompat-v7:27.1.1'
      implementation 'com.android.support:design:27.1.1'
      implementation 'com.android.support.constraint:constraint-layout:1.1.2'
      implementation 'com.android.support:design:27.1.1'
      implementation 'com.android.support:support-v4:27.1.1'
  
      //firebase
      implementation 'com.google.firebase:firebase-firestore:11.8.0'
      implementation 'com.google.firebase:firebase-core:16.0.1'
      implementation 'com.firebaseui:firebase-ui-auth:3.1.0'
      implementation 'com.google.firebase:firebase-auth:11.2.2'
  
      //picasso
      implementation 'com.squareup.picasso:picasso:2.71828'
  
  
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.2'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
  }
  
  apply plugin: 'com.google.gms.google-
  </code></pre>
  
  <p><strong>And here is project Build Gradle:</strong> </p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  
  buildscript {
      ext.kotlin_version = '1.2.30'
      repositories {
          google()
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.1.4'
          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:4.0.2'
      }
  }
  
  allprojects {
      repositories {
          google()
          jcenter()
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>