title: Android Studio: Cannot resolve symbol ‘RequestConfiguration’
body: <p>I am modifying an android app, which used to work, but the test ad is no longer loaded and in the Android Studio log I see:</p>
  
  <p><em>Use RequestConfiguration.Builder().setTestDeviceIds(Arrays.asList("8B…D76C") to get test ads on this device.</em></p>
  
  <p>I tried to add that to the code, but I get a “Cannot resolve symbol ‘RequestConfiguration’.
  Unfortunately Android Studio is not suggesting what's the package which needs to be imported.</p>
  
  <p>This is how the code look after adding the requested line. </p>
  
  <pre><code>RequestConfiguration.Builder().setTestDeviceIds(Arrays.asList("device_id_3");
  
  AdRequest adRequest = new AdRequest.Builder()
        // Add a test device to show Test Ads
        .addTestDevice(“device_id_1") 
        .addTestDevice("device_id_2")
        .addTestDevice("device_id_3") 
        .build();
  
  // Load ads into Banner Ads
  adView.loadAd(adRequest);
  </code></pre>