title: Google Gson 2.4 minifyEnable true issue
body: <p>I work on an app that currently uses google gson 1.7.1 lib. It all works fine, but i wanted to update it to the latest version. Tried updating it to 2.4 and on the debug variant of the app it works well.</p>
  
  <p>I recently tried running the app on the release version and suddenly the JSON parsing mechanism is not working. Reverting the gson lib to 1.7.1 fixes the issue, but i would still want to have it updated to the latest version.</p>
  
  <p>What i have noticed is that if i set <code>minifyEnabled</code> to <code>false</code> on the release version, i start getting data again (the parsing mechanism works).</p>
  
  <p>Does anyone know of an issue regarding <code>minifyEnabled true</code> and the latest gson lib ?</p>
  
  <p>In my proguard-rules files i have the following items related to the gson lib:</p>
  
  <pre><code>-keepclassmembers class com.myapp.data.beans.json.** {
      private &lt;fields&gt;;
  }
  -keep class sun.misc.Unsafe { *; }
  -keep class com.myapp.ui.views.** { *; }
  -keepattributes Signature
  -keepattributes *Annotation*
  </code></pre>
  
  <p>I also tried adding </p>
  
  <pre><code>-keep class * implements com.google.gson.TypeAdapterFactory
  -keep class * implements com.google.gson.JsonSerializer
  -keep class * implements com.google.gson.JsonDeserializer
  </code></pre>
  
  <p>as per Google Gson sample <a href="https://github.com/google/gson/blob/master/examples/android-proguard-example/proguard.cfg" rel="nofollow noreferrer">config</a> file but it does not make any difference.</p>