@java.lang.Override
  public void writeTo(com.google.protobuf.CodedOutputStream output) throws java.io.IOException {
    if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(languageCode_)) {
      com.google.protobuf.GeneratedMessageV3.writeString(output, 1, languageCode_);
    }
    if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(name_)) {
      com.google.protobuf.GeneratedMessageV3.writeString(output, 2, name_);
    }
    if (ssmlGender_
        != com.google.cloud.texttospeech.v1.SsmlVoiceGender.SSML_VOICE_GENDER_UNSPECIFIED
            .getNumber()) {
      output.writeEnum(3, ssmlGender_);
    }
    if (((bitField0_ & 0x00000001) != 0)) {
      output.writeMessage(4, getCustomVoice());
    }
    if (((bitField0_ & 0x00000002) != 0)) {
      output.writeMessage(5, getVoiceClone());
    }
    getUnknownFields().writeTo(output);
  }
<pre>
Optional. The configuration for a voice clone. If
[VoiceCloneParams.voice_clone_key] is set, the service chooses the voice
clone matching the specified configuration.
</pre>

<code>
.google.cloud.texttospeech.v1.VoiceCloneParams voice_clone = 5 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/VoiceSelectionParams.java