@Override
  public @NotNull DomElementsProblemsHolder getProblemHolder(DomElement element) {
    if (element == null || !element.isValid()) return EMPTY_PROBLEMS_HOLDER;
    final DomFileElement<DomElement> fileElement = DomUtil.getFileElement(element);

    synchronized (LOCK) {
      final XmlTag tag = fileElement.getRootElement().getXmlTag();
      if (tag != null) {
        DomElementsProblemsHolder readyHolder = myHolders.get(tag);
        if (readyHolder != null) {
          return readyHolder;
        }
      }
      return EMPTY_PROBLEMS_HOLDER;
    }
  }
@Override
  public @NotNull DomElementsProblemsHolder getProblemHolder(DomElement element)