title: Prevent Proguard from removing empty constructor of fragment
body: <p>You know, all subclasses of Fragment must include a public empty constructor but when using proguard these constructors will be removed. I have specified below commands but empty constructor still be removed. Can anyone help me to keep empty constructor of Fragment? Thanks you.</p>
  
  <pre><code>-keepclassmembers public class * extends android.support.v4.app.Fragment { 
     public &lt;init&gt;(***);
     #public &lt;init&gt;(); //already tried this
  }
  
  -keepclassmembers public class * extends com.xxx.MyFragment { 
     public &lt;init&gt;(***);
     #public &lt;init&gt;(); //already tried this
  }
  </code></pre>