def request_payload(cls, request, request_id):
        '''JSON v2 request (or notification) payload.'''
        payload = {
            'jsonrpc': '2.0',
            'method': request.method,
        }
        # A notification?
        if request_id is not None:
            payload['id'] = request_id
        # Preserve empty dicts as missing params is read as an array
        if request.args or request.args == {}:
            payload['params'] = request.args
        return payload