map in a JFrame using url

I'm trying to add a google-map in my frame, I read here that the best way is opening an URL, so, I did:

    JTextPane myMap = new JTextPane();
     JScrollPane scroll = new JScrollPane();
     scroll.getViewport().add(myMap);
 
 
     scroll.setBounds(40,240,1200,644);
     background.add(scroll);
 
     try{
         URL url = getClass().getResource("/html/maps.html");
 
         myMap.setPage(url);
     } catch (Exception e) {
         e.printStackTrace();
     }
 

But I see nothing, if I use helloWorld.html instead of maps.htm I see the content.

Why is it happening?

Thank you in advance

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