fix: Replace unreleased InitialSubscribeRequest initial_cursor field with initial_location

Author: parthea

google/cloud/pubsublite_v1/types/subscriber.py

@@ -50,18 +50,16 @@ class InitialSubscribeRequest(proto.Message):
  The partition from which to receive messages. Partitions are
  zero indexed, so ``partition`` must be in the range [0,
  topic.num_partitions).
- initial_cursor (google.cloud.pubsublite_v1.types.Cursor):
- Optional. Initial stream delivery cursor,
- pointing to anywhere in the topic partition.
- Cursors past head result in stream breakage. If
- not set, messages will be delivered from the
- commit cursor for the given subscription and
- partition.
+ initial_location (google.cloud.pubsublite_v1.types.SeekRequest):
+ Optional. Initial target location within the
+ message backlog. If not set, messages will be
+ delivered from the commit cursor for the given
+ subscription and partition.
  """
 
  subscription = proto.Field(proto.STRING, number=1,)
  partition = proto.Field(proto.INT64, number=2,)
- initial_cursor = proto.Field(proto.MESSAGE, number=3, message=common.Cursor,)
+ initial_location = proto.Field(proto.MESSAGE, number=4, message="SeekRequest",)
 
 
 class InitialSubscribeResponse(proto.Message):
@@ -79,9 +77,11 @@ class InitialSubscribeResponse(proto.Message):
 class SeekRequest(proto.Message):
  r"""Request to update the stream's delivery cursor based on the
  given target. Resets the server available tokens to 0.
+ SeekRequests past head result in stream breakage.
+
  SeekRequests may not be sent while another SeekRequest is
  outstanding (i.e., has not received a SeekResponse) on the same
- stream. SeekRequests past head result in stream breakage.
+ stream.
 
  Attributes:
  named_target (google.cloud.pubsublite_v1.types.SeekRequest.NamedTarget):