`getComponent` of my custom `FileEditor` is never called

I wish to make my own file type to edit some lineage graphs graphically.

I have derived from `FileEditor` class 

public class LineageFileEditor implements FileEditor {

   @Override public @NotNull JComponent getComponent() {
      return new JExample();
   }

   ...

and also wrote a custom component, which draws a circle

public class JExample extends JComponent {

   @Override protected void paintComponent(Graphics g) {
      Graphics2D g2 = (Graphics2D)g;

      g.fillOval(10, 10, 100, 100);
   }

   public static void main(String[] args) {
      JFrame frame = new JFrame();

      frame.add(new JExample(), BorderLayout.CENTER);

      frame.setSize(800, 600);
      frame.setLocationRelativeTo(null);
      frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

      frame.setVisible(true);
   }
}

This component works from it's main.

Unfortunately, my editor acts as just text editor in IntelliJ

and `#getComponent()` method is never called according to the debugger.

Why and how to fix?