@java.lang.Override
  public com.google.cloud.texttospeech.v1.VoiceSelectionParamsOrBuilder getVoiceOrBuilder() {
    return voice_ == null
        ? com.google.cloud.texttospeech.v1.VoiceSelectionParams.getDefaultInstance()
        : voice_;
  }
<pre>
Required. The desired voice of the synthesized audio.
</pre>

<code>
.google.cloud.texttospeech.v1.VoiceSelectionParams voice = 1 [(.google.api.field_behavior) = REQUIRED];
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1/src/main/java/com/google/cloud/texttospeech/v1/StreamingSynthesizeConfig.java