title: Android :app:transformClassesWithJarMergingForDebug FAILED - ZipException: duplicate entry
body: <p>Sorry if I asked a duplicate question, but I couldn't find a solution for this error. I surfed around stackoverflow,gradle site, android blogs, google search but there wasn't a working solution for several hours. I'm an android beginner so I not sure if I have missed something in other posts.</p>
  
  <pre><code>apply plugin: 'com.android.application'
  apply plugin: 'com.google.gms.google-services'
  
  android {
           compileSdkVersion 23
           buildToolsVersion "23.0.0"
  
  defaultConfig {
      minSdkVersion 14
      targetSdkVersion 22
      multiDexEnabled true
  }
  buildTypes {
      release {
          minifyEnabled false
          proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
      }
  }
  }
  
  dependencies {
  compile 'com.android.support:appcompat-v7:22.2.1.'
  compile 'com.squareup.retrofit:retrofit:2.0.0-beta1'
  compile 'com.squareup.retrofit:converter-gson:2.0.0-beta1'
  compile 'com.android.support:recyclerview-v7:22.2.1.'
  compile 'com.android.support:cardview-v7:22.2.1.'
  compile 'com.squareup.picasso:picasso:2.5.2'
  compile 'com.pnikosis:materialish-progress:1.7'
  compile 'com.jakewharton:butterknife:7.0.1'
  compile 'com.google.android.gms:play-services:8.1.0'
  compile files('libs/android-support-v4-22.2.1.jar')
  compile files('libs/applovin-sdk-6.0.1.jar')
  compile files('libs/appodeal-1.13.1.jar')
  compile files('libs/chartboost-5.2.0.jar')
  compile files('libs/my-target-4.0.13.jar')
  compile files('libs/unity-ads-1.4.7.jar')
  }
  </code></pre>
  
  <p>The project was working fine until I add some libs from appodeal (those compile file lines). I have tried to build the project but gradle gave the errors.</p>
  
  <pre><code>:app:transformClassesWithJarMergingForDebug'.
  com.android.build.transform.api.TransformException: java.util.zip.ZipException: duplicate entry: android/support/v7/widget/RecyclerView$ItemDecoration.class
  </code></pre>
  
  <p>There are also 2 more error of the same exception about duplicate entry- not sure why I got them: <code>android/support/v4/PrintKitKat.class</code> and  <code>android/support/multidex/MultiDex$V14.class</code>. </p>
  
  <p>I tried to upgrade gradle, invalidate and restart to clear cache, omit dependencies then rebuild/clean project, find potential duplicate module to exclude, and search projects for those <code>.class</code> but I found no duplication.</p>