private void ensureEnableTimePointingIsMutable() {
      if (!((bitField0_ & 0x00000008) != 0)) {
        enableTimePointing_ = new java.util.ArrayList<java.lang.Integer>(enableTimePointing_);
        bitField0_ |= 0x00000008;
      }
    }
<pre>
Required. The configuration of the synthesized audio.
</pre>

<code>
.google.cloud.texttospeech.v1beta1.AudioConfig audio_config = 3 [(.google.api.field_behavior) = REQUIRED];
</code>
java-texttospeech/proto-google-cloud-texttospeech-v1beta1/src/main/java/com/google/cloud/texttospeech/v1beta1/SynthesizeSpeechRequest.java