@java.lang.Override
    public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
      if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(bucketName_)) {
        com.google.protobuf.GeneratedMessageV3.writeString(output, 1, bucketName_);
      }
      if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(path_)) {
        com.google.protobuf.GeneratedMessageV3.writeString(output, 2, path_);
      }
      if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(endpoint_)) {
        com.google.protobuf.GeneratedMessageV3.writeString(output, 3, endpoint_);
      }
      if (dataProviderCase_ == 4) {
        output.writeMessage(
            4,
            (com.google.storagetransfer.v1.proto.TransferTypes.S3CompatibleMetadata) dataProvider_);
      }
      if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(region_)) {
        com.google.protobuf.GeneratedMessageV3.writeString(output, 5, region_);
      }
      getUnknownFields().writeTo(output);
    }
<pre>
A S3 compatible metadata.
</pre>

<code>.google.storagetransfer.v1.S3CompatibleMetadata s3_metadata = 4;</code>
java-storage-transfer/proto-google-cloud-storage-transfer-v1/src/main/java/com/google/storagetransfer/v1/proto/TransferTypes.java