title: What is the purpose of onGetRoot() and onLoadChildren() in MediaBrowserServiceCompat?
body: <p>I am a beginner in Android Development trying to create a media player with the implementation of <code>MediaBrowser</code> and <code>MediaSession</code>.</p>
  
  <p>I am confused with the function of <code>onGetRoot()</code> and <code>onLoadChildren()</code>.</p>
  
  <ol>
  <li>My first question is in <code>layman's term</code> what is the purpose of these two methods.  </li>
  <li>What is the root they are pertaining in <code>onGetRoot()</code>? What I have in mind is, it is the root of the directory, am I correct?</li>
  <li>What is the children pertaining in <code>onLoadChildren()</code>? what I have in mind is the list of music in the root, am I correct?</li>
  <li>Will this <code>onLoadchildren()</code> return the actual playlist?</li>
  </ol>