@Nullable
  public ModuleWizardStep getPreviousStep(ModuleWizardStep step) {
    final List<ModuleWizardStep> steps = getSelectedSteps();
    final int i = steps.indexOf(step);
    return i > 0 ? steps.get(i - 1) : null;
  }
@Nullable
  public ModuleWizardStep getPreviousStep(ModuleWizardStep step)