JPanel covers part JFrame border

Question

I have a class that extends JPanel.

public class SomethingClass extends JPanel implements ActionListener{

When I add this class (which extends JPanel) to a JFrame it covers the JFrames very think black line border on the south side and east side.

It looks messy as the JFrame border on the east side is still there. I would like to get the JFrame to have a border on its south and west edges but I am stumped.

This is an image of the GUI:

I create the JFrame in my main method like this:

    SomethingClass something = new SomethingClass();
    JFrame frame = new JFrame(something); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   
    frame.getContentPane().add(new SomethingClass());
    frame.setSize(400, 200);
    frame.setResizable(false);
    frame.setVisible(true);