@Nullable
  @Override
  protected JComponent createCenterPanel() {
    JPanel mainPanel = new JPanel(new BorderLayout());

    JBSplitter splitPane = new JBSplitter(0.3f);
    splitPane.setSplitterProportionKey(getSplitterProportionKey());

    splitPane.setFirstComponent(createMasterView());
    splitPane.setSecondComponent(createDetailView());

    mainPanel.add(splitPane, BorderLayout.CENTER);

    return mainPanel;
  }
@Nullable
  @Override
  protected JComponent createCenterPanel()