How to create a BigQuery TransferConfig that overwrites the destination tables using the Python API

I want to automatically create a BigQuery DataTransfer using the Python Client API. I am already able to create it successfully and also to trigger it. However, my problem is that I want to set the flag overwrite_destination_table to True. I can manually do that in the TransferConfig UI, however, I am not able to find any way of passing this flag via the Client API.

Question, does anybody know a way to set the flag overwrite_destination_table for BigQuery DataTranfer in code?

You can specify the option using params:

import os
import datetime
from google.cloud import bigquery_datatransfer, bigquery_datatransfer_v1

transfer_client = bigquery_datatransfer.DataTransferServiceClient()

project_id = os.getenv('PROJECT_ID')
dataset_id = os.getenv('BIGQUERY_DATASET')
service_account_name = os.getenv('BIGQUERY_SERVICE_ACCOUNT')
display_name = os.getenv('SCHEDULE_NAME')

query_string = """
SELECT * FROM demo_bq_dataset.demo_table;
"""

parent = transfer_client.common_project_path(project_id)

transfer_config = bigquery_datatransfer.TransferConfig(
    destination_dataset_id=dataset_id,
    display_name=display_name,
    data_source_id="scheduled_query",
    params={
        "query": query_string,
        "destination_table_name_template": "demo_destination_table",
        "overwrite_destination_table": True,
    },
    schedule="every 4 hours synchronized",
    schedule_options=bigquery_datatransfer_v1.types.ScheduleOptions(
        start_time=datetime.datetime.now(datetime.timezone.utc)
    )
)

transfer_config = transfer_client.create_transfer_config(
    bigquery_datatransfer.CreateTransferConfigRequest(
        parent=parent,
        transfer_config=transfer_config,
        service_account_name=service_account_name,
    )
)

print("Created scheduled query '{}'".format(transfer_config.name))