@Nullable
  private static String getAdditionalDocumentation(PsiElement elem) {
    final XmlTag xmlTag = PsiTreeUtil.getParentOfType(elem, XmlTag.class);
    if (xmlTag == null) {
      return null;
    }
    final AntDomElement antElement = AntSupport.getAntDomElement(xmlTag);
    if (antElement instanceof AntFilesProvider) {
      final List<File> list = ((AntFilesProvider)antElement).getFiles(new HashSet<>());
      if (list.size() > 0) {
        final @NonNls StringBuilder builder = new StringBuilder();
        final XmlTag tag = antElement.getXmlTag();
        if (tag != null) {
          builder.append("<b>");
          builder.append(tag.getName());
          builder.append(":</b>");
        }
        for (File file : list) {
          if (builder.length() > 0) {
            builder.append("<br>");
          }
          builder.append(file.getPath());
        }
        return builder.toString();
      }
    }
    return null;
  }
@Nullable
  private static String getAdditionalDocumentation(PsiElement elem)