@java.lang.Override
  public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
    if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(parent_)) {
      com.google.protobuf.GeneratedMessageV3.writeString(output, 1, parent_);
    }
    if (sourceCase_ == 2) {
      output.writeMessage(2, (com.google.cloud.translate.v3.FileInputSource) source_);
    }
    if (sourceCase_ == 3) {
      output.writeMessage(3, (com.google.cloud.translate.v3.GcsInputSource) source_);
    }
    getUnknownFields().writeTo(output);
  }
<pre>
Google Cloud Storage file source.
</pre>

<code>.google.cloud.translation.v3.GcsInputSource gcs_input_source = 3;</code>
java-translate/proto-google-cloud-translate-v3/src/main/java/com/google/cloud/translate/v3/ImportAdaptiveMtFileRequest.java