title: android google drive api cannot query folder
body: <p>All files are in the MetadataBuffer,but folder not included.</p>
  
  <pre><code>            Tasks.await(driveClient.requestSync());
              Query q = new Query.Builder()
                      .addFilter(Filters.in(SearchableField.PARENTS, rootFolder.getDriveId()))
                      .addFilter(Filters.eq(SearchableField.TRASHED, false))
                      .build();
              Task&lt;MetadataBuffer&gt; queryTask = driveResourceClient.query(q);
              MetadataBuffer query = Tasks.await(queryTask);
              for (int i = 0; i &lt; query.getCount(); i++) {
                  Log.d(TAG, query.get(i).getTitle());
              }
  </code></pre>
  
  <p>how to list children folder as well?</p>
  
  <p>I have try .addFilter(Filters.eq(SearchableField.MIME_TYPE, "application/vnd.google-apps.folder")) already, doesn't work too..</p>
  
  <p>Thanks</p>