code: function (container) {
                  var raw = ariaUtilsObject.keys(container);
                  return ariaUtilsArray.filter(raw, function (key) {
                      return !aria.utils.Json.isMetadata(key);
                  });
              }
docs: Retrieves all non metadata keys of a JSON object
  @param {Object} container reference to the data holder object
  @return {Array} an array containing all non metadata keys of the object
  @see aria.utils.Object.keys