title: Duplicate class from androidx.core:core:1.0.0 and com.android.support:support-compat:26.1.0
body: <p>This is my  <code>build.gradle</code>:</p>
  
  <pre><code>buildscript {
      repositories {
          maven { url 'https://maven.fabric.io/public' }
      }
  
      dependencies {
          classpath 'io.fabric.tools:gradle:1.+'
      }
  }
  apply plugin: 'com.android.application'
  apply plugin: 'io.fabric'
  apply plugin: 'kotlin-android'
  apply plugin: 'kotlin-android-extensions'
  
  repositories {
      maven { url 'https://maven.fabric.io/public' }
      google()
  }
  
  
  android {
      compileSdkVersion 26
      buildToolsVersion '26.0.2'
      useLibrary 'org.apache.http.legacy'
      defaultConfig {
          multiDexEnabled true
          minSdkVersion 16
          targetSdkVersion 26
          compileOptions {
              sourceCompatibility JavaVersion.VERSION_1_7
              targetCompatibility JavaVersion.VERSION_1_7
          }
          renderscriptTargetApi 22
          renderscriptSupportModeEnabled true
      }
      buildTypes {
          debug {
              debuggable true
              buildConfigField "boolean", "CRASH_LOGGING", "true"
              applicationIdSuffix ".dev"
          }
          release {
              debuggable false
              buildConfigField "boolean", "CRASH_LOGGING", "true"
              minifyEnabled true
              proguardFiles 'proguard-project.txt'
          }
      }
  
      flavorDimensions "regular"
  
      dexOptions {
          javaMaxHeapSize "4g"
      }
  }
  
  dependencies {
      compile "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
      compile 'com.android.support:multidex:1.0.2'
      compile 'com.android.support:design:26.1.0'
      compile 'com.android.support:recyclerview-v7:26.1.0'
      compile 'com.android.support:appcompat-v7:26.1.0'
      compile 'com.android.support:cardview-v7:26.1.0'
      implementation "com.android.support:support-compat:26.1.0"
      compile 'com.google.android.gms:play-services-auth:16.0.1'
      compile 'com.google.android.gms:play-services-ads:11.8.0'
  
      compile('com.thoughtworks.xstream:xstream:1.4.7') {
          exclude group: 'xmlpull', module: 'xmlpull'
      }
      compile 'org.apache.commons:commons-lang3:3.6'
      compile 'joda-time:joda-time:2.9.9'
      compile('org.simpleframework:simple-xml:2.7.1') {
          exclude module: 'stax'
          exclude module: 'stax-api'
          exclude module: 'xpp3'
      }
      compile group: 'com.google.code.gson', name: 'gson', version: '2.7'
  
      // UI &amp; VIEWS
      compile 'com.tuyenmonkey:mkloader:1.4.0'
      compile 'com.mikhaellopez:circularimageview:3.0.2'
      compile 'com.github.mmin18:realtimeblurview:1.1.0'
      compile 'com.github.PhilJay:ValueBar:v1.0.2'
  
      // IMAGE HANDLING
      compile 'com.nostra13.universalimageloader:universal-image-loader:1.9.5'
  
      // NETWORK HANDLING
      compile 'com.android.volley:volley:1.0.0'
      compile 'com.squareup.okhttp3:okhttp:3.9.0'
  
      //RETORFIT
      compile 'com.squareup.retrofit2:retrofit:2.3.0'
      compile 'com.squareup.retrofit2:converter-gson:2.3.0'
      compile('com.squareup.retrofit2:converter-simplexml:2.3.0') {
          exclude module: 'stax'
          exclude module: 'stax-api'
          exclude module: 'xpp3'
      }
      compile 'com.squareup.retrofit2:converter-scalars:2.3.0'
  
      // FABRIC
      compile('com.crashlytics.sdk.android:crashlytics:2.7.1@aar') {
          transitive = true;
      }
  
      // ADS
      compile 'com.flurry.android:analytics:8.2.0@aar'
      compile 'com.appbrain:appbrain-sdk:14.60@aar'
      compile(name: 'android-ad-sdk', ext: 'aar')
      compile(name: 'SOMAAndroid-9.1.5-release', ext: 'aar')
      compile 'com.applovin:applovin-sdk:+'
  
      compile 'com.android.support.constraint:constraint-layout:1.0.2'
  
      samsungDebugImplementation files('libs/sdk-v1.0.0.jar')
      samsungDebugImplementation files('libs/motion-v2.2.2.jar')
      samsungReleaseImplementation files('libs/sdk-v1.0.0.jar')
      samsungReleaseImplementation files('libs/motion-v2.2.2.jar')
  
      //debug DB
      debugCompile 'com.amitshekhar.android:debug-db:1.0.1'
  
  }
  
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>And when i upgrade this line:</p>
  
  <pre><code>compile 'com.google.android.gms:play-services-ads:18.3.0'
  </code></pre>
  
  <p>I get this error:</p>
  
  <pre><code>Duplicate class android.support.v4.app.INotificationSideChannel found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.app.INotificationSideChannel$Stub found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.app.INotificationSideChannel$Stub$Proxy found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.os.IResultReceiver found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.os.IResultReceiver$Stub found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.os.IResultReceiver$Stub$Proxy found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.os.ResultReceiver found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.os.ResultReceiver$1 found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.os.ResultReceiver$MyResultReceiver found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  Duplicate class android.support.v4.os.ResultReceiver$MyRunnable found in modules core-1.0.0-runtime.jar (androidx.core:core:1.0.0) and support-compat-26.1.0-runtime.jar (com.android.support:support-compat:26.1.0)
  </code></pre>
  
  <p>This is the <code>build.gradle</code> file:</p>
  
  <pre><code>// Top-level build file where you can add configuration options common to all sub-projects/modules.
  buildscript {
      ext.kotlin_version = "1.3.10"
      repositories {
          google()
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.5.2'
          classpath 'com.google.gms:google-services:4.3.2'
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
          classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"
      }
  }
  
  allprojects {
      repositories {
          jcenter()
          flatDir {
              dirs 'libs'
          }
  
          // For MobFox
          maven {
              url "https://jitpack.io"
          }
          // For AppBrain SDK
          maven {
              url 'http://swisscodemonkeys.github.io/appbrain-sdk/maven'
          }
      }
  }
  </code></pre>
  
  <p>Any idea what creates this Duplicate error? How I can fix it?</p>