Lists the parameters visible to this client.

        Parameters are returned in lexicographical order.

        :param str parameter_type: The type of parameter
        :rtype: :class:`.Parameter` iterator

def list_parameters(self, parameter_type=None, page_size=None):
        """Lists the parameters visible to this client.

        Parameters are returned in lexicographical order.

        :param str parameter_type: The type of parameter
        :rtype: :class:`.Parameter` iterator
        """
        params = {'details': True}

        if parameter_type is not None:
            params['type'] = parameter_type
        if page_size is not None:
            params['limit'] = page_size

        return pagination.Iterator(
            client=self._client,
            path='/mdb/{}/parameters'.format(self._instance),
            params=params,
            response_class=mdb_pb2.ListParametersResponse,
            items_key='parameter',
            item_mapper=Parameter,
        )