Explicitly specify arguments of server_groups creation

Create API call expectes two parameters - name and policies[*]. It is not a
complex structure, so there is no reason to support kwargs. It is better to
specify explicitly all expected parameters.

PS: removing support of kwargs is "backward compatible", since we have
validation at API side and usage of additional parameters was an error
previously.

[*] - https://developer.openstack.org/api-ref/compute/?expanded=create-server-group-detail

Change-Id: I8b40b0db450287bbc5ee8d69834aa764353dbd98

novaclient/v2/server_groups.py

@@ -84,10 +84,15 @@ class ServerGroupsManager(base.ManagerWithFind):
         """
         return self._delete('/os-server-groups/%s' % id)
 
-    def create(self, **kwargs):
+    def create(self, name, policies):
         """Create (allocate) a server group.
 
+        :param name: The name of the server group.
+        :param policies: Policy name or a list of exactly one policy name to
+            associate with the server group.
         :rtype: list of :class:`ServerGroup`
         """
-        body = {'server_group': kwargs}
+        policies = policies if isinstance(policies, list) else [policies]
+        body = {'server_group': {'name': name,
+                                 'policies': policies}}
         return self._create('/os-server-groups', body, 'server_group')

novaclient/v2/shell.py

@@ -4280,9 +4280,8 @@ def do_server_group_list(cs, args):
     help=_('Policies for the server groups.'))
 def do_server_group_create(cs, args):
     """Create a new server group with the specified details."""
-    kwargs = {'name': args.name,
-              'policies': args.policy}
-    server_group = cs.server_groups.create(**kwargs)
+    server_group = cs.server_groups.create(name=args.name,
+                                           policies=args.policy)
     _print_server_group_details(cs, [server_group])