private void visitXPathVariableReference(XPathVariableReference reference) {
          if (referenceName.equals(reference.getReferencedName())) {
            if (reference.resolve() == null) {
              usages.add(PsiTreeUtil.getContextOfType(reference, XmlTag.class, true));
            }
          }
        }
private void visitXPathVariableReference(XPathVariableReference reference)