title: Cannot resolve symbol '@string/default_notification_channel_id'
body: <p>I am trying to set up a Firebase Cloud Messaging Client app on Android. I am using <a href="https://github.com/firebase/quickstart-android/tree/master/messaging" rel="noreferrer">https://github.com/firebase/quickstart-android/tree/master/messaging</a> as a guideline or template for my implementation. When I try to write the code at <a href="https://github.com/firebase/quickstart-android/blob/master/messaging/app/src/main/AndroidManifest.xml" rel="noreferrer">https://github.com/firebase/quickstart-android/blob/master/messaging/app/src/main/AndroidManifest.xml</a>, I see the <code>Cannot resolve symbol '@string/default_notification_channel_id'</code> error in the following line:</p>
  
  <pre><code>&lt;meta-data
          android:name="com.google.firebase.messaging.default_notification_channel_id"
          android:value="@string/default_notification_channel_id"/&gt;
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/zpiFD.png" rel="noreferrer"><img src="https://i.stack.imgur.com/zpiFD.png" alt="enter image description here"></a></p>
  
  <p>Do you have any ideas about a fix for this error? Thank you.</p>