title: ParentReference or Google_ParentReference
body: <p>In Google documentation ( <a href="https://developers.google.com/drive/v2/reference/files/insert" rel="nofollow">https://developers.google.com/drive/v2/reference/files/insert</a> ) has the following code snippets:</p>
  
  <pre><code>$file = new Google_DriveFile();
    ...
  $parent = new ParentReference();
  </code></pre>
  
  <p>I am getting error in <code>Fatal error: Class 'ParentReference' not found</code>. I grepped the <em>google-api-php-client</em> for <em>ParentReference</em>.</p>
  
  <pre><code>lib: grep -R ParentReference ./ | grep class
  .../Google_DriveService.php:class Google_ParentReference extends Google_Model {
  </code></pre>
  
  <p>It is seems that there are some prefix "Google_" added and <em>ParentReference</em> is renamed to  *Google_ParentReference* .</p>
  
  <p>My conclusion is right? Is there something else I couldn't understand?</p>