code: public FacesConfigNavigationRuleType<FacesConfigType<T>> getOrCreateNavigationRule()
     {
        List<Node> nodeList = childNode.get("navigation-rule");
        if (nodeList != null &&  nodeList.size() > 0)
        {
           return new FacesConfigNavigationRuleTypeImpl<FacesConfigType<T>>(this, "navigation-rule", childNode, nodeList.get(0));
        }
        return createNavigationRule();
     }
docs: If not already created, a new <code>navigation-rule</code> element will be created and returned.
  Otherwise, the first existing <code>navigation-rule</code> element will be returned.
  @return the instance defined for the element <code>navigation-rule</code>