protected AnAction @NotNull [] createGroupingActions() {
    List<UsageGroupingRuleProvider> providers = UsageGroupingRuleProvider.EP_NAME.getExtensionList();
    List<AnAction> list = new ArrayList<>(providers.size());
    for (UsageGroupingRuleProvider provider : providers) {
      ContainerUtil.addAll(list, provider.createGroupingActions(this));
    }
    sortGroupingActions(list);
    moveActionTo(list, UsageViewBundle.message("action.group.by.module"),
                 UsageViewBundle.message("action.flatten.modules"), true);
    return list.toArray(AnAction.EMPTY_ARRAY);
  }
protected AnAction @NotNull [] createGroupingActions()