code: String getLink(JsonNode linkNode) {
  		// Handle both representations of a link: as a string or as an object
  		// http://jsonapi.org/format/#document-links (v1.0)
  		if (linkNode.has(HREF)) {
  			// object form
  			return linkNode.get(HREF).asText();
  		}
  		return linkNode.asText(null);
  	}
docs: Accepts a JsonNode which encapsulates a link.  The link may be represented as a simple string or as
  <a href="http://jsonapi.org/format/#document-links">link</a> object.  This method introspects on the
  {@code linkNode}, returning the value of the {@code href} member, if it exists, or returns the string form
  of the {@code linkNode} if it doesn't.
  <p>
  <em>Package-private for unit testing.</em>
  </p>
  @param linkNode a JsonNode representing a link, may return {@code null}
  @return the link URL