Set access_policy for messaging's dispatcher

oslo.messaging allow dispatcher to restrict endpoint methods since
5.11.0 in I42239e6c8a8be158ddf5c3b1773463b7dc93e881, set with
LegacyRPCAccessPolicy explicitly to ensure it's compatible and
fix FutureWarning like:

"The access_policy argument is changing its default value to <class
'oslo_messaging.rpc.dispatcher.DefaultRPCAccessPolicy'> in version '?',
please update the code to explicitly set None as the value:
access_policy defaults to LegacyRPCAccessPolicy which exposes private
methods. Explicitly set access_policy to DefaultRPCAccessPolicy or
ExplicitRPCAccessPolicy.

Change-Id: Ia8922baf422ee84e55f05534678b2f0377843688

neutron/common/rpc.py

@@ -22,6 +22,7 @@ from neutron_lib import exceptions as lib_exceptions
 from oslo_config import cfg
 from oslo_log import log as logging
 import oslo_messaging
+from oslo_messaging.rpc import dispatcher
 from oslo_messaging import serializer as om_serializer
 from oslo_service import service
 from oslo_utils import excutils
@@ -171,8 +172,10 @@ def get_client(target, version_cap=None, serializer=None):
 def get_server(target, endpoints, serializer=None):
     assert TRANSPORT is not None
     serializer = RequestContextSerializer(serializer)
+    access_policy = dispatcher.LegacyRPCAccessPolicy
     return oslo_messaging.get_rpc_server(TRANSPORT, target, endpoints,
-                                         'eventlet', serializer)
+                                         'eventlet', serializer,
+                                         access_policy=access_policy)
 
 
 def get_notifier(service=None, host=None, publisher_id=None):

neutron/tests/unit/common/test_rpc.py

@@ -20,6 +20,7 @@ import mock
 from oslo_config import cfg
 import oslo_messaging as messaging
 from oslo_messaging import conffixture as messaging_conffixture
+from oslo_messaging.rpc import dispatcher
 import testtools
 
 from neutron.common import rpc
@@ -167,8 +168,10 @@ class TestRPC(base.DietTestCase):
         server = rpc.get_server(tgt, ends, serializer='foo')
 
         mock_ser.assert_called_once_with('foo')
+        access_policy = dispatcher.LegacyRPCAccessPolicy
         mock_get.assert_called_once_with(rpc.TRANSPORT, tgt, ends,
-                                         'eventlet', ser)
+                                         'eventlet', ser,
+                                         access_policy=access_policy)
         self.assertEqual('server', server)
 
     def test_get_notifier(self):