title: Is "@Keep support annotation" rule in proguard-android-optimize.txt still applicable when using AndroidX?
body: <p>It is common to apply <code>proguard-android-optimize.txt</code> as proguard file.</p>
  
  <pre><code>proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-project.txt'
  </code></pre>
  
  <p>However, when I went through the content of <code>proguard-android-optimize.txt</code></p>
  
  <pre><code>...
  
  -keepclassmembers class **.R$* {
      public static &lt;fields&gt;;
  }
  
  # The support library contains references to newer platform versions.
  # Don't warn about those in case this app is linking against an older
  # platform version.  We know about them, and they are safe.
  -dontwarn android.support.**
  
  # Understand the @Keep support annotation.
  -keep class android.support.annotation.Keep
  
  -keep @android.support.annotation.Keep class * {*;}
  
  -keepclasseswithmembers class * {
      @android.support.annotation.Keep &lt;methods&gt;;
  }
  
  -keepclasseswithmembers class * {
      @android.support.annotation.Keep &lt;fields&gt;;
  }
  
  -keepclasseswithmembers class * {
      @android.support.annotation.Keep &lt;init&gt;(...);
  }
  </code></pre>
  
  <p>I was wondering, if such rule still applicable, if we were using AndroidX instead of support library? Should we add the following rules explicitly in our project <code>proguard-project.txt</code>?</p>
  
  <pre><code># Understand the @Keep support annotation.
  -keep class androidx.annotation.Keep
  
  -keep @androidx.annotation.Keep class * {*;}
  
  -keepclasseswithmembers class * {
      @androidx.annotation.Keep &lt;methods&gt;;
  }
  
  -keepclasseswithmembers class * {
      @androidx.annotation.Keep &lt;fields&gt;;
  }
  
  -keepclasseswithmembers class * {
      @androidx.annotation.Keep &lt;init&gt;(...);
  }
  </code></pre>