@Nullable
    @Override
    public String getLocationString() {
      if (!isValid()) {
        return null;
      }

      if (ContainerUtil.getFirstItem(getCompositeChildren()) instanceof MarkdownParagraph) {
        final MarkdownCompositePsiElementBase element = findChildByClass(MarkdownCompositePsiElementBase.class);
        assert element != null;
        return StringUtil.shortenTextWithEllipsis(element.getText(), PRESENTABLE_TEXT_LENGTH, 0);
      }
      else {
        return null;
      }
    }
@Nullable
    @Override
    public String getLocationString()