title: Android ProGuard: can't find referenced class
body: <p>Running ProGuard in my Android Studio Project I get warnings like this: </p>
  
  <pre><code>Warning: com.google.common.collect.Maps: can't find referenced class javax.annotation.Nullable
  </code></pre>
  
  <p>I might solve this with one of this variants: </p>
  
  <p>1</p>
  
  <pre><code>-keep class com.google.common.collect.** { *; }
  -dontwarn com.google.common.collect.**
  </code></pre>
  
  <p>2 </p>
  
  <pre><code>-keep class javax.annotation.** { *; }
  -dontwarn javax.annotation.**
  </code></pre>
  
  <p><strong>What is the best way to solve the above warning? What is the difference between variant 1. and 2.?</strong></p>