title: proguard-android-optimize.txt vs proguard-android.txt in Android build.gradle
body: <p>I was reading <a href="https://developer.android.com/studio/build/shrink-code" rel="noreferrer">the docs about shrinking, obfuscating and optimising for a release build using build.gradle for an Android app</a>. In one section of the docs, <strong><code>proguard-android.txt</code></strong> is used as the defauly ProGuard file:</p>
  
  <pre><code>android {
      ...
      buildTypes {
          release {
              shrinkResources true
              minifyEnabled true
              proguardFiles getDefaultProguardFile('proguard-android.txt'),
                      'proguard-rules.pro'
          }
      }
  }
  </code></pre>
  
  <p>and in another section, <strong><code>proguard-android-optimize.txt</code></strong> is used:</p>
  
  <pre><code>android {
      ...
      buildTypes {
          release {
              shrinkResources true
              minifyEnabled true
              proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'),
                      'proguard-rules.pro'
          }
      }
  }
  </code></pre>
  
  <p>There doesn't seem to be an explanation of what the difference between these are, and I can't find any information. Can someone explain what the differences are and when you would use <strong><code>proguard-android-optimize.txt</code></strong> vs <strong><code>proguard-android.txt</code></strong>?</p>
  
  <p>Thanks :)</p>