/// <summary>
        /// Creates binding for $ref scenario
        /// </summary>
        /// <param name="associationResourceInstance"></param>
        /// <returns></returns>
        private void CreateLinkPayload(AssociationResourceInstance associationResourceInstance, XmlElement parentNode)
        {
            XmlElement bindElement;
            bindElement = this.CreateDataWebMetadataElement("ref");

            if (associationResourceInstance.Operation == AssociationOperation.Add)
                bindElement.InnerText = CreateCanonicalUri(associationResourceInstance.ResourceInstanceKey);
            else
            {
                XmlAttribute nullAttribute = CreateDataWebMetadataAttribute("null");
                nullAttribute.Value = "true";
                bindElement.Attributes.Append(nullAttribute);
            }

            if (parentNode == null)
                document.AppendChild(bindElement);
            else
                parentNode.AppendChild(bindElement);
        }
        private void CreateBinding(AssociationResourceInstance keyedResourceInstance, XmlNode parentNode)
        {
            XmlElement entryElement = CreateBasicEntryElement(keyedResourceInstance, parentNode);

            XmlElement idNode = CreateIdElement(keyedResourceInstance);
            entryElement.AppendChild(idNode);
        }