title: Firebase core dependency : Program type already present: android.support.v4.app.INotificationSideChannel
body: <p>After including Firebase core dependency in my project </p>
  
  <pre><code>implementation 'com.google.firebase:firebase-core:15.0.2'
  </code></pre>
  
  <p>I am getting this error.</p>
  
  <blockquote>
    <p>Program type already present:
    android.support.v4.app.INotificationSideChannel Message{kind=ERROR,
    text=Program type already present:
    android.support.v4.app.INotificationSideChannel, sources=[Unknown
    source file], tool name=Optional.of(D8)}</p>
  </blockquote>
  
  <p>I went through a few similar questions but none of them seem to solve my error.</p>
  
  <p>Here is my app level <code>build.gradle</code>:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 28
      buildToolsVersion "28.0.2"
      defaultConfig {
          applicationId "com.example.chandranichatterjee.appname"
          minSdkVersion 15
          targetSdkVersion 28
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation 'androidx.appcompat:appcompat:1.0.0-alpha1'
      //implementation 'com.google.firebase:firebase-core:11.2.0'
      implementation 'com.google.firebase:firebase-core:15.0.2'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'androidx.test:runner:1.1.0-alpha3'
      androidTestImplementation 'androidx.test.espresso:espresso-core:3.1.0-alpha3'
  }
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>Below is my project level <code>build.gradle</code>:</p>
  
  <pre><code>buildscript {
  
      repositories {
          google()
          jcenter()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.1.0'
          classpath 'com.google.gms:google-services:4.0.1'
  
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          google()
          jcenter()
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  
  <p>I have also included below lines in <code>gradle.properties</code>:</p>
  
  <pre><code>android.useAndroidX=true
  android.enableJetifier=true
  </code></pre>
  
  <p>Any help is appreciated. Thanks!</p>