title: What is the purpose of using square brackets in Java code comment?
body: <p>I saw some Java code by Google using square bracket in comment.<br>
  For example:</p>
  
  <pre><code>// [START initialize_auth]
  mAuth = FirebaseAuth.getInstance();
  // [END initialize_auth]
  </code></pre>
  
  <p>Is there any special purpose for this style?</p>