@java.lang.Override
  public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
    getSerializedSize();
    if (((bitField0_ & 0x00000001) != 0)) {
      output.writeMessage(1, getInput());
    }
    if (((bitField0_ & 0x00000002) != 0)) {
      output.writeMessage(2, getVoice());
    }
    if (((bitField0_ & 0x00000004) != 0)) {
      output.writeMessage(3, getAudioConfig());
    }
    if (getEnableTimePointingList().size() > 0) {
      output.writeUInt32NoTag(34);
      output.writeUInt32NoTag(enableTimePointingMemoizedSerializedSize);
    }
    for (int i = 0; i < enableTimePointing_.size(); i++) {
      output.writeEnumNoTag(enableTimePointing_.get(i));
    }
    if (((bitField0_ & 0x00000008) != 0)) {
      output.writeMessage(8, getAdvancedVoiceOptions());
    }
    getUnknownFields().writeTo(output);
  }
<pre>
Advanced voice options.
</pre>

<code>
optional .google.cloud.texttospeech.v1beta1.AdvancedVoiceOptions advanced_voice_options = 8;
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/SynthesizeSpeechRequest.java