title: Android Library project OkHttp3 proguard
body: <p>I have an android project with a library project module, in which I am using Retrofit with OkHttp3 to do API requests. I need to use Proguard to obfuscate the project, but when I do, I get a huge list of errors relating to OkHttp when trying to build the signed apk:</p>
  
  <pre><code>can't find referenced class javax.annotation.Nullable
  can't find referenced class javax.annotation.ParametersAreNonnullByDefault
  </code></pre>
  
  <p>I have tried to following rules in both the main app and library project Proguard files, but nothing seems to work:</p>
  
  <pre><code> -dontwarn javax.annotation.Nullable
   -dontwarn javax.annotation.ParametersAreNonnullByDefault
  </code></pre>
  
  <p>Any help would be hugely appreciated.</p>