questionpanel in extensionpanel

public class ExtensionPanel extends JPanel {
private QuestionPanel questionPanel;
public ExtensionPanel() {
        setPreferredSize(new Dimension(360, 300));
        setLayout(new BorderLayout());
        initChildPanel();
    }
private void initChildPanel() {
        // init
        questionPanel = new QuestionPanel();
        // add
        add(questionPanel, BorderLayout.CENTER);
    }
public QuestionPanel getQuestionPanel() {
        return questionPanel;
    }
}