title: Android Studio - ProGuard IOException Duplicate Zip Entry
body: <p>So I am trying to set up ProGuard in Gradle for my Android Studio project and I get the following error when building the project:</p>
  
  <blockquote>
    <p>Error:Execution failed for task ':app:proguardDebug'.
    java.io.IOException: Can't write [C:\Users\Rich\Desktop\WebProjects\AndroidStudioProjects\Roomie\app\build\intermediates\classes-proguard\debug\classes.jar] (Can't read C:\Users\Rich\Desktop\WebProjects\AndroidStudioProjects\Roomie\app\libs\bolts-android-1.1.4.jar(;;;;;;!META-INF/MANIFEST.MF)] (Duplicate zip entry [a/a.class == bolts-android-1.1.4.jar:bolts/AggregateException.class]))</p>
  </blockquote>
  
  <p>Here is my proguard-rules.pro</p>
  
  <pre><code>-keep class butterknife.** { *; }
  -dontwarn butterknife.internal.**
  -keep class **$$ViewInjector { *; }
  
  -dontwarn org.apache.http.annotation.**
  
  -keepclasseswithmembernames class * {
      @butterknife.* &lt;fields&gt;;
  }
  
  -keepclasseswithmembernames class * {
      @butterknife.* &lt;methods&gt;;
  }
  </code></pre>