private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.texttospeech.v1beta1.VoiceCloneParams,
            com.google.cloud.texttospeech.v1beta1.VoiceCloneParams.Builder,
            com.google.cloud.texttospeech.v1beta1.VoiceCloneParamsOrBuilder>
        getVoiceCloneFieldBuilder() {
      if (voiceCloneBuilder_ == null) {
        voiceCloneBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.texttospeech.v1beta1.VoiceCloneParams,
                com.google.cloud.texttospeech.v1beta1.VoiceCloneParams.Builder,
                com.google.cloud.texttospeech.v1beta1.VoiceCloneParamsOrBuilder>(
                getVoiceClone(), getParentForChildren(), isClean());
        voiceClone_ = null;
      }
      return voiceCloneBuilder_;
    }
<pre>
Optional. The configuration for a voice clone. If
[VoiceCloneParams.voice_clone_key] is set, the service will choose the
voice clone matching the specified configuration.
</pre>

<code>
.google.cloud.texttospeech.v1beta1.VoiceCloneParams voice_clone = 5 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/VoiceSelectionParams.java