public Builder mergeAwsS3CompatibleDataSource(
          com.google.storagetransfer.v1.proto.TransferTypes.AwsS3CompatibleData value) {
        if (awsS3CompatibleDataSourceBuilder_ == null) {
          if (dataSourceCase_ == 19
              && dataSource_
                  != com.google.storagetransfer.v1.proto.TransferTypes.AwsS3CompatibleData
                      .getDefaultInstance()) {
            dataSource_ =
                com.google.storagetransfer.v1.proto.TransferTypes.AwsS3CompatibleData.newBuilder(
                        (com.google.storagetransfer.v1.proto.TransferTypes.AwsS3CompatibleData)
                            dataSource_)
                    .mergeFrom(value)
                    .buildPartial();
          } else {
            dataSource_ = value;
          }
          onChanged();
        } else {
          if (dataSourceCase_ == 19) {
            awsS3CompatibleDataSourceBuilder_.mergeFrom(value);
          } else {
            awsS3CompatibleDataSourceBuilder_.setMessage(value);
          }
        }
        dataSourceCase_ = 19;
        return this;
      }
<pre>
An AWS S3 compatible data source.
</pre>

<code>.google.storagetransfer.v1.AwsS3CompatibleData aws_s3_compatible_data_source = 19;
</code>
java-storage-transfer/proto-google-cloud-storage-transfer-v1/src/main/java/com/google/storagetransfer/v1/proto/TransferTypes.java