code: function (item, options, serializerInstance) {
                  if (serializerInstance) {
                      if ("serialize" in serializerInstance) {
                          return serializerInstance.serialize(item, options);
                      } else {
                          this.$logError(this.INVALID_JSON_SERIALIZER_INSTANCE);
                          return null;
                      }
                  }
  
                  return this.__defaultJsonSerializer.serialize(item, options);
              }
docs: Converts an object to a JSON string
  @param {Object|Array|String|Number|Boolean|Date|RegExp|Function} item item to serialize
  @param {Object} options options for the serialize method of the serializer - optional
  @param {Object} serializerInstance instance of a serializer - optional. If not provided, an instance of
  the default serializer (aria.utils.json.JsonSerializer) is used. If the provided instance does not have a
  serialize method, an error is raised
  @return {String} the JSON string. null if the JSON serialization failed