title: Compilation error while upgrading from Guava 19 to 20
body: <p>Trying to upgrade guava from version 19 to 20 and getting this error:</p>
  
  <pre><code>Error:java: cannot access com.google.errorprone.annotations.CanIgnoreReturnValue
    class file for com.google.errorprone.annotations.CanIgnoreReturnValue not found
  </code></pre>
  
  <p>Any ideas how to fix it? I don't have any references to errorprone in my project.
  Adding dependency to <code>errorprone</code> like below doesn't help:</p>
  
  <pre><code>        &lt;groupId&gt;com.google.errorprone&lt;/groupId&gt;
          &lt;artifactId&gt;error_prone_annotations&lt;/artifactId&gt;
  </code></pre>