title: Nested Grid not generating in Ext JS 6.2
body: <p><strong><em>Hi Techies</em></strong>,
     I have created the nested Grid in Ext JS 6.2 with the help of "Rowwidget" plugin. However I have get the outer Grid. But, it does not shown the inner grid.</p>
  
  <p>I followed this <a href="http://examples.sencha.com/extjs/6.2.0-ea/examples/kitchensink/#row-widget-grid" rel="noreferrer">Sencha code example</a></p>
  
  <p>My code avaiable in:
      <a href="https://fiddle.sencha.com/#fiddle/1ed9" rel="noreferrer">Sencha Fiddle</a></p>
  
  <p>Thanks in advance...</p>