Support specifying batch_size when submitting batch predict jobs #525
Description
The BatchPredictionJob REST API supports configuring the number of records sent to the machine replica in each batch via ManualBatchTuningParameters.
While ManualBatchTuningParameters is implemented in this library, I don't see any way to specify it when submitting a batch predict job.
Describe the solution you'd like
Add batch_size kwarg to models.Model.batch_predict and jobs.BatchPredictionJob.create and add it to the gapic_batch_prediction_job instance.