'Returns a googledatastore.PropertyOrder representation of the order.
Args:
adapter: A datastore_rpc.AbstractAdapter.'

def _to_pb_v1(self, adapter):

    v1_order = googledatastore.PropertyOrder()
    adapter.get_query_converter().v3_order_to_v1_order(self.__order, v1_order)
    return v1_order
