API call:  update a sink resource.

        :type project: str
        :param project: ID of the project containing the sink.

        :type sink_name: str
        :param sink_name: the name of the sink

        :type filter_: str
        :param filter_: the advanced logs filter expression defining the
                        entries exported by the sink.

        :type destination: str
        :param destination: destination URI for the entries exported by
                            the sink.

        :type unique_writer_identity: bool
        :param unique_writer_identity: (Optional) determines the kind of
                                       IAM identity returned as
                                       writer_identity in the new sink.

        :rtype: dict
        :returns: The sink resource returned from the API (converted from a
                  protobuf to a dictionary).

def sink_update(
        self, project, sink_name, filter_, destination, unique_writer_identity=False
    ):
        """API call:  update a sink resource.

        :type project: str
        :param project: ID of the project containing the sink.

        :type sink_name: str
        :param sink_name: the name of the sink

        :type filter_: str
        :param filter_: the advanced logs filter expression defining the
                        entries exported by the sink.

        :type destination: str
        :param destination: destination URI for the entries exported by
                            the sink.

        :type unique_writer_identity: bool
        :param unique_writer_identity: (Optional) determines the kind of
                                       IAM identity returned as
                                       writer_identity in the new sink.

        :rtype: dict
        :returns: The sink resource returned from the API (converted from a
                  protobuf to a dictionary).
        """
        path = "projects/%s/sinks/%s" % (project, sink_name)
        sink_pb = LogSink(name=path, filter=filter_, destination=destination)
        sink_pb = self._gapic_api.update_sink(
            path, sink_pb, unique_writer_identity=unique_writer_identity
        )
        # NOTE: LogSink message type does not have an ``Any`` field
        #       so `MessageToDict`` can safely be used.
        return MessageToDict(sink_pb)