code: protected Item updateItem(Item item,
                                JsonNode jsonItem) throws RepositoryException {
          if (item instanceof Node) {
              return updateNode((Node) item, jsonItem);
          }
          return updateProperty((Property) item, jsonItem);
      }
docs: Updates the existing item based upon the supplied JSON content.
  
  @param item     the node or property to be updated
  @param jsonItem the JSON of the item(s) to be updated
  @return the node that was updated; never null
  @throws javax.jcr.RepositoryException if any other error occurs