title: Android Studio: gradle's experimental plugin and ProGuard's files
body: <p>I use <code>gradle</code>'s experimental plugin in order to add some <code>NDK</code> code.
  before usage of <code>NDK</code> support my <code>buildTypes</code> section was next </p>
  
  <pre><code>buildTypes {
          release {
              minifyEnabled true
              proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
          }
      }
  </code></pre>
  
  <p>as you can see here I use optimized options of ProGuard.
  And when I started to use <code>gradle</code>'s experimental plugin I changed those lines to</p>
  
  <pre><code>buildTypes {
          release {
              minifyEnabled true
              proguardFiles.add(file('proguard-rules.pro'))
          }
      }
  </code></pre>
  
  <p>The question is next: is it ok to use such options when I want to use <code>'proguard-android-optimize.txt'</code> file? </p>
  
  <p>If not then how I could define that I want to use <code>'proguard-android-optimize.txt'</code> file with <code>gradle</code>'s experimental plugin?</p>