Docstring for MapField indicates it's a Sequence

[busunkim96]

https://github.com/googleapis/python-aiplatform/blob/a94d79a922afdb6612889c652d45ddd4f2c10c2f/google/cloud/aiplatform_v1beta1/types/endpoint.py#L31-L102

traffic_split is a proto.MapField but the type annotation indicates it is a sequence. I think Mapping[str, int] is what this field behaves like in practice.

Note that there's no TrafficSplitEntry type in the library, so the existing type is misleading.

        traffic_split (Sequence[~.endpoint.Endpoint.TrafficSplitEntry]):
            A map from a DeployedModel's ID to the
            percentage of this Endpoint's traffic that
            should be forwarded to that DeployedModel.
            If a DeployedModel's ID is not listed in this
            map, then it receives no traffic.
            The traffic percentage values must add up to
            100, or map must be empty if the Endpoint is to
            not accept any traffic at a moment.

    traffic_split = proto.MapField(proto.STRING, proto.INT32, number=5)

CC @sirtorry

[tseaver]

Even worse, now that we are generating typing, is that the type declaration for the parameter includes the non-existent Entry class.