@Nullable
  @Override
  protected JComponent createCenterPanel() {
    final Project project = myOldMethod.getProject();
    final VirtualFile file = PsiUtilCore.getVirtualFile(myOldMethod);

    DiffContentFactory contentFactory = DiffContentFactory.getInstance();
    @Nls String methodCallPrefix = JavaRefactoringBundle.message("suggest.signature.preview.method.call.prefix");
    DocumentContent oldContent = contentFactory.create(myOldMethod.getText() + "\n\n\n" + methodCallPrefix + "\n " + myOldCall.getText(), file);
    DocumentContent newContent = contentFactory.create(myNewMethod.getText() + "\n\n\n" + methodCallPrefix + "\n " + myNewCall.getText(), file);
    SimpleDiffRequest request = new SimpleDiffRequest(null, oldContent, newContent,
                                                      JavaRefactoringBundle.message("suggest.signature.preview.title.before"),
                                                      JavaRefactoringBundle.message("suggest.signature.preview.after.title"));

    DiffRequestPanel diffPanel = DiffManager.getInstance().createRequestPanel(project, getDisposable(), null);
    diffPanel.putContextHints(DiffUserDataKeys.PLACE, DIFF_PLACE);
    diffPanel.setRequest(request);

    final JPanel panel = new JPanel(new BorderLayout());
    panel.add(diffPanel.getComponent(), BorderLayout.CENTER);
    panel.setBorder(IdeBorderFactory.createEmptyBorder(JBUI.insetsTop(5)));
    return panel;
  }
@Nullable
  @Override
  protected JComponent createCenterPanel()