private static void addBeforeAfterTemplateFilesGutterIcon(PsiElement highlightingElement,
                                                            PsiDirectory descriptionDirectory,
                                                            Collection<? super RelatedItemLineMarkerInfo<?>> result) {
    final List<PsiFile> templateFiles = new SortedList<>(Comparator.comparing(PsiFileSystemItem::getName));
    for (PsiFile file : descriptionDirectory.getFiles()) {
      final String fileName = file.getName();
      if (fileName.endsWith(".template")) {
        if (fileName.startsWith("after.") ||
            fileName.startsWith("before.")) {
          templateFiles.add(file);
        }
      }
    }
    if (templateFiles.isEmpty()) return;

    //noinspection DialogTitleCapitalization
    final RelatedItemLineMarkerInfo<PsiElement> info = NavigationGutterIconBuilder
      .create(DevKitIcons.Gutter.Diff, CONVERTER, RELATED_ITEM_PROVIDER)
      .setTargets(templateFiles)
      .setPopupTitle(DevKitBundle.message("gutter.related.navigation.popup.template.title"))
      .setTooltipText(DevKitBundle.message("gutter.related.navigation.popup.template.tooltip"))
      .setAlignment(GutterIconRenderer.Alignment.RIGHT)
      .createLineMarkerInfo(highlightingElement);
    result.add(info);
  }
private static void addBeforeAfterTemplateFilesGutterIcon(PsiElement highlightingElement,
                                                            PsiDirectory descriptionDirectory,
                                                            Collection<? super RelatedItemLineMarkerInfo<?>> result)