private static void doCheckRefs(final XmlElement element, final ProblemsHolder holder) {
    for (PsiReference ref : element.getReferences()) {
      ProgressManager.checkCanceled();
      if (XmlHighlightVisitor.hasBadResolve(ref, true)) {
        if (ref.getElement() instanceof XmlElementContentSpec) {
          final String image = ref.getCanonicalText();
          if (image.equals("-") || image.equals("O")) continue;
        }
        holder.registerProblem(ref);
      }
    }
  }
private static void doCheckRefs(final XmlElement element, final ProblemsHolder holder)