@Override
  public void fillRelatedFiles(final @NotNull XmlFile xmlFile, final @NotNull Set<? super PsiFile> resultSet) {
    HtmlLinkUtil.processLinks(xmlFile, tag -> {
      final XmlAttribute attribute = tag.getAttribute("href");
      if (attribute == null) {
        return true;
      }

      final XmlAttributeValue link = attribute.getValueElement();
      if (link == null) {
        return true;
      }

      for (PsiReference reference : link.getReferences()) {
        if (reference instanceof PsiPolyVariantReference) {
          final ResolveResult[] results = ((PsiPolyVariantReference)reference).multiResolve(false);

          for (ResolveResult result : results) {
            final PsiElement resolvedElement = result.getElement();
            if (resolvedElement instanceof PsiFile) {
              resultSet.add((PsiFile)resolvedElement);
            }
          }
        }
        else {
          final PsiElement resolvedElement = reference.resolve();
          if (resolvedElement instanceof PsiFile) {
            resultSet.add((PsiFile)resolvedElement);
          }
        }
      }
      return true;
    });
  }
@Override
  public void fillRelatedFiles(final @NotNull XmlFile xmlFile, final @NotNull Set<? super PsiFile> resultSet)