title: How to list subfolder content when using Android DocumentFile API
body: <p>I'm trying to switch to the DocumentFile API as Android doesn't allow using File API anymore...</p>
  <p>When I select a folder, it returned URI is</p>
  <pre><code>content://com.android.externalstorage.documents/tree/primary%3AMedia%2FCamera%2FFreeTime
  </code></pre>
  <p>Now I'm calling</p>
  <pre><code> DocumentFile.fromTreeUri(this, uri)
  </code></pre>
  <p>to get the content of the folder. I want to keep a list of all the subfolders within</p>
  <p>The 1st subfolder I found has the following URI</p>
  <pre><code>content://com.android.externalstorage.documents/tree/primary%3AMedia%2FCamera%2FFreeTime/document/primary%3AMedia%2FCamera%2FFreeTime%2F11
  </code></pre>
  <p>I need to save it so later on I can check the files within that folder</p>
  <p>The problem is that when I try to call</p>
  <pre><code> DocumentFile.fromTreeUri(this, uri)
  </code></pre>
  <p>on this subfolder uri it returns a DocumentFile matching the parent folder of this subfolder</p>
  <pre><code>content://com.android.externalstorage.documents/tree/primary%3AMedia%2FCamera%2FFreeTime
  </code></pre>
  <p>How can I save the subfolder uri here so I can later on list this subfolder files?</p>