@Nullable
  public static AntDomAntlib getAntLib(PsiFile psiFile) {
    if (psiFile instanceof XmlFile) {
      final DomManager domManager = DomManager.getDomManager(psiFile.getProject());
      final DomFileElement<AntDomAntlib> fileElement = domManager.getFileElement((XmlFile)psiFile, AntDomAntlib.class);
      return fileElement != null? fileElement.getRootElement() : null;
    }
    return null;
  }
@Nullable
  public static AntDomAntlib getAntLib(PsiFile psiFile)