title: Cloud Firestore : DexArchiveMergerException Unable to merge dex
body: <p>when I include:</p>
  
  <blockquote>
    <p>compile 'com.firebaseui:firebase-ui-firestore:3.1.0'</p>
  </blockquote>
  
  <p>build fails. firestore version 3.0.0 is same result.</p>
  
  <p>without this code, build is success.</p>
  
  <p>Is there duplicated module? please help me.</p>
  
  <blockquote>
    <p>Error:Execution failed for task
    ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.</p>
    
    <blockquote>
      <p>java.lang.RuntimeException: java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge
      dex</p>
    </blockquote>
  </blockquote>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 26
      defaultConfig {
          applicationId "com.android"
          minSdkVersion 16
          targetSdkVersion 26
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
  
          // firebase
          resConfigs "auto"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      implementation fileTree(dir: 'libs', include: ['*.jar'])
      implementation 'com.android.support:appcompat-v7:26.1.0'
      implementation 'com.android.support.constraint:constraint-layout:1.0.2'
      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'
  
      // volley
      compile 'com.android.volley:volley:1.0.0'
  
      // firebase, map, location
      implementation 'com.google.android.gms:play-services-maps:11.4.2'
      implementation 'com.google.android.gms:play-services-location:11.4.2'
  
      // firebase storage
      compile 'com.google.firebase:firebase-storage:11.4.2'
  
      // FirebaseUI for Firebase Auth
      compile 'com.firebaseui:firebase-ui-auth:3.1.0'
  
      // Required only if Facebook login support is required
      compile 'com.facebook.android:facebook-login:4.27.0'
  
      // Required only if Twitter login support is required
      compile("com.twitter.sdk.android:twitter-core:3.0.0@aar") { transitive = true }
  
      // glide
      compile 'com.github.bumptech.glide:glide:4.3.1'
      annotationProcessor 'com.github.bumptech.glide:compiler:4.3.1'
  
      // FirebaseUI Storage
      compile 'com.firebaseui:firebase-ui-storage:3.1.0'
  
      // Firebase cloud message
      compile 'com.google.firebase:firebase-messaging:11.4.2'
  
      // FirebaseUI for Cloud Firestore
      compile 'com.firebaseui:firebase-ui-firestore:3.1.0'
  }
  
  // firebase
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <hr>
  
  <pre><code>buildscript {
  
      repositories {
          google()
          jcenter()
  
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.0.0'
          //firebase
          classpath 'com.google.gms:google-services:3.1.0'
  
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          google()
          jcenter()
  
  
          // glide
          mavenCentral()
          maven { url 'https://maven.google.com' }
  
          // firebase twitter login
          maven { url 'https://maven.fabric.io/public' }
  
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>