https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquerydatatransfer/latest/com.google.cloud.bigquery.datatransfer.v1.TransferRun.DestinationCase
Enum TransferRun.DestinationCase (2.91.0) | Java client libraries | Google Cloud Documentation
https://docs.cloud.google.com/java/docs/reference/google-cloud-bigquerydatatransfer/latest/com.google.cloud.bigquery.datatransfer.v1.TransferRun.Builder
Class TransferRun.Builder (2.91.0) | Java client libraries | Google Cloud Documentation